Why is your condensing combi boiler not condensing.
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- Опубликовано: 27 сен 2024
- #saveenergy #gassafe #energy #energysavings Derek takes a look to see why condensing boilers are not condensing and what we can do about it to make them condense and save us gas, money and co2 production.
Enjoyed this , much of this is something I've often spoken about, trying to explain to customers that they would be better having a smaller combination boiler than the 37kw recommend by a competitor.. thanks for your efforts,I'll use this video for future reference for customers..
Great stuff thanks for your efforts 👍😊
Fantastic content Derek! You make it very interesting and have a great way of teaching without mind clogging jargon . About time we got our heads around this as fitters. Looking forward to the weather comp video . Cheers
Good advice, I've used the service menu on my Greenstar CDi 30 to set Max. output (heating) to be 50%. Also set the HW temp so I only need a tiny amount of cold water mixed in the shower. I always use a dishwasher so don't need piping hot water for doing dishes.
Great video. I am in the US and while I had to do some conversions on the numbers by and large the same principles exist here. I could tell my new boiler (Dunkirk - not sure if you have those over there) was way over powered for my home when it was only cycling on for 2 to 3 minutes at a time. I reduced the target temp and high limit to 160 F and the system cycles much more reasonably now (fires on for 10-12 minutes and only cycles about twice an hour).
Great Video very few engineers understand about rating boilers for different homes.
Sadly not all boilers allow you to range rate. Hopefully it will become mandatory soon at the manufacturing process.
Very interesting video Derek. Only thing I would add is, even if you get the return temp down to 54 how much gas are you saving, 4% at best, but probably 3 or even 2%.
So between £20 and £40 per year on a £1000 gas bill. Seems pointless to me.
Brilliant rebound, on commissioning a boiler I do hot water then heating, on a service I just do high and low.
I’ve just an Ideal vogue system boiler installed with hot water priority and weather comp.
The boiler runs mostly around 45 to 50 deg flow and 38 to 45 return on heating so is always in condensing mode.
With hot water it’s heating at 80 deg, but that’s only for 40 mins a day in total
Thank you. Couldn't some of the discrepancy between the boiler set water temp and the actual temp coming out of the tap depend on the accuracy of the temperature sensor and thermostat in the boiler?
Food for thought Derek... great stuff cheers pal.
Not sure how you find the time to produce such informative videos but yet again another brilliant presentation, learning so much from them. Mega Thanks.
How can i do my calcs? I have 16 rads, 3 of which are towel rails, 11 are double rads and 1 single. I have an 835 Vailant Combi. Modern home, good insulation etc, i also run underfloor heating off the boiler in one 20sqm room. What should i rate the boiler down to please?
Derek, your a genius mate
hi can you please supply a link to your explanation on heat only boilers ie range rating .thanks
I have always wondered why my Vaillant combi condensing boiler still 'plumes' even with the flow temperature is only 50c. Surely all the water vapour should condense and flue gas should be invisible?
Turned my water down to 45 degrees and also the preheat function is now off. I switched off my weather comp on my Worcester as the heating was on longer than necessary and using more gas. It’s a digital one so it comes from the local weather services via a Worcester server then the controls are updated. Maybe then I also had all radiators on maximum.
Hi Derek, great educational video and certainly food for thought in these energy conscious times.
So staying on that subject, you hinted on one interesting subject 'Range Rating' almost a black art subject.
My question is this, concidering very new system boilers, what's the difference between 'range rating' and 'modulation'
All I understand is RR involves changing fan speed, so can reducing a 30 Kw system boiler to 28 or 26 Kw at the same output temperature realy reduce energy consumption and if so how. Maybe there is a very clear explaination on line that you could link me to. Kind regards Dave Porter
I am sorting videos out for this so watch this space
Hi. I'm not a professional, just a consumer. But unless I have missed something in this video, the larger boiler uses less gas, so surely it would cost me less to run. Is that correct?
No lots of if buts and maybe
Will be very interested in your forthcoming video regarding system boilers. This is what I have in my house (Vaillant EcoTec Plus 630), a 230L Megaflo and a 'full' tado installation including eTRVs on every radiator (along with separate schedules for each room and set points of 19C). The one big challenge is that tado does not have functionality to modulate the flow temperature depending on the call for heat (hot water / heating) so I am forced to have a set point of 60C for water and heating so as to remove the risk of legionaires in the water tank. Would appreciate your thoughts on how to maximise the efficiency of the overall system.
If you had a weather compensation module on the boiler your heating flow temperature could be considerably lower than 60c for much of the time. I have it on a simple Y plan set up and it works well. It obviously doesn't apply to the hot water tank flow temp, but I'd say the risk of legionella in a closed domestic system is low, You could run the HW at 50-55c then once a week run it at 60c for a day. That would kill anything off. Otherwise your system looks pretty darned close to what I'd like to have if I were starting with a blank sheet of paper. Nice one !
I'm using a Tado which I believe includes weather compensation . Do you think I should still Install an external weather compensator.
Not really revelant to my system boiler installed last ear. 30Kw. I had a conventional 80,000BTU floor mounted CF. The installer said we take about a third so = 30KW. Well l it has cut gas consumption b a massive amount but kept the house warm. So happy. Just had it serviced t £90. The old one hardly needed looking at so there is a new cost.
How many kw is needed to heat 9liters a min by say 35c I personally have range rated my hot water to 15kw and have it set on 45 at moment and it runs good for now
Very good video derek.
I think consumers are switching on to having an efficient system now with the bills being so high
Good video, explained in laymans terms. Its a shame that it has taken the energy crisis for everyone to talk about modulation, condensing and range rating.😉 I have a Vaillant 837 which was bought for the 15ltr flow rate, as I have 2 en suites. It was installed in 2009 and has been running at max heating of 29KW! There was no talk of range rating it and weather compensation etc. I've worked the heat loss out on the back of a fag packet to about 11KW, So have now range rated it to the min of 12KW. It will interesting how it performs this winter. Back to the Video, I'm not a gas fitter, but even though the higher rate boiler you were testing didn't seem to be able to keep to the hot water temps you in putted! It used less gas, so would be cheaper to run.? I think this needs to be looked into to further👍
Hi mate any update on this?
I am replacing Brittony 11T somewhat reluctantly as simple tends to be best! we heat with balanced flue wallheaters 40 years old! Cost of pilot a significant cost with current gas costs .The Rinnai powered flue spark ignition my choice. Condensing or non condensing? Condensing more efficient,costs more. non condensing cost less less efficient whichis the best choice?
8litres a minute struck a chord!
Flow rates in my area in the south east are generally poor.
But when I cast my mind back to traditional tank fed hot and cold systems, over the years the skills of plumbers of old who understood the relationship with head of water and pipe sizing has diminished.
Consequently end users have generally got used to lower flow rates, especially with the advent of ceramic discs and flexy connections.
When consumers, especially any with cylinder storage systems, are made aware of the energy they use to heat water; in conjunction with the price of energy, I can see major lifestyle adjustments.
Provisionally, my meagre research suggests a two person household consumes 2-7kw per day in gas to heat water (combi-storage).
Given 6-8kw for heating your average home (given -1C ambient),
the hot water side of the equation takes on takes on a whole new meaning. In summary to repeat what you've said, range rate your boiler, lower water temperature and with stored water also heat only immediately before use.
Range rate?
@@simonstones1918 Back in the stone age, boilers came with gas valves who's output pressure to burner could be adjusted within the boilers minimum to maximum output; example, a 50,000 Btu boiler ( about 15kw) could be set at lower pressures and therefore lower heat outputs, but not random ie. Two or three outputs between 40,000 and 50,000 Btu's. determined by burner pressure.
@@johnward5006 thanks. But what is this range rating with new boilers….or is that in affect, modulating…?
@@simonstones1918 Very good question. Any new boiler can be range rated. This is particularly relevant with combis whose outputs will be determined by the hot water requirements.
On the heating side, the maximum output can be adjusted to suit the heat loss of the building without affecting hot water performance.
During burner operation, the boiler will modulate to maintain the required set temperatures. If the heating output is not matched to the buildings heat loss, the boiler will struggle to modulate close enough.
Example: 30kw boiler, heat loss 6kw, boiler modulation 3to1 means boiler will step down to 10kw.
Set boiler heating output to say 7kw the result is modulation between 7kw and 2.3ishkw.
Great video. Quick question can you do the same on a storage combi because there is some storage so you need to maintain a higher water temp because of legionaires disease?
You should be able to on the heating and it depends if the stored combi has an anti legionella device
Surely you can adjust the tap flow using the service valve.Most plumbing has them these days.
Good educational video , Thanks
Hi Derek,
Why would you use a heat only boiler instead of a system boiler?
If you have a solid fuel stove/range and the water from this open vented side of the system shouldn't pass through the heat exchanger of a gas boiler wouldn't a system boiler with an additional heat exchanger installed always be the better option over a heat only boiler when you can't fully avail of the open vented system already in place.
If the water from the gas boiler and the solid fuel stove are allowed to mix then I can see the benefit of the heat only boiler.
Is this correct as I have been told?
Thank you for your time 👍🏼
System boilers are more efficient than open vented boilers but sometimes there isn’t room for a system boiler.
@@tomkatgastraining Easy to convert an open vent regular boiler,r remove header tank and fit expansion vessel as you know boilers running at 1 atmosphere (1 bar) heat more efficently and no heat loss through header tank or vent pipe ,worth a video explaining how to convert using modern boilers,keep up those great videos.
You getting into a whole different issue, but I get where your coming from.
@@tomkatgastraining When changing like for like I wouldn't necessarily agree that a system boiler would be more efficient.
That said I'm as guilty as any for not range rating until recently, although pre condensing boilers I did it as a matter of course.
Currently working on a bit of project assessing domestic hot water energy consumption.Your, yet again, brilliantly presented video has given me food for thought with my project.
@@tomkatgastraining but can you link a heat only boiler (open vent gas boiler)with a solid fuel heating system without an additional heat exchanger or do the 2 need to be separated with an additional heat exchanger as with a system boiler and solid fuel boiler.
Thanks to anyone who knows the answer in advance.
Top tip, if you have a cold-fill washing machine and a combi. Fill a watering-can with hot from the tap, then pour that into the machine via the detergent drawer when it's filling.
Hard to believe that 80% of UK houses have combi boilers. Are 80% of UK houses really sub 2 bed, 1 bathroom. I have a heat only system and the biggest problem is the radiators just aren't big enough to lose enough heat so they get very hot but the house can be cold and the boiler constantly cycles.
The majority definitely have combi boilers, not all properties with combi boilers only have 1 bathroom either, that's what they were originally designed for though. The larger the kW boiler generally means more flow rate that's why oversized boilers are fitted unfortunately, but they are rarely ever range rated down
You may need to balance your rad down.
The lockshield valve should only be open an 1/8 to 1/2 a turn.
That's because i think us end users prefer the convieniance of hot water on demand. and rightly so. heating a full tank of water just for a few sinks of hot water.
You either have an insulation or damp problem or a system design problem ( rads a bit small maybe, or not convectors) I live in an 1885 three bedroom stone house and my 18kw heat only boiler with weather comp keeps the house warm enough at a flow temp currently at 48c-55c ( the weather comp varies the flow temp relative to outside temp, but overall it runs much cooler than having the room stat rule by switching to full on/off). You would get less cycling by turning the boiler thermostat ( not the roomstat) down a bit and trying to maintain a lower more even heat output that is constant during the timed 'on' period. This reduces the hot/cold on/off effect you are experiencing. Lots of stuff to think about there. Good luck !
Quick question for everyone. My rads are cold at the bottom (2 year old system so not sludge). I run the system at 50 degrees for the reasons derek says in this vid. Is that the reason for rads being cold at the bottom?
You need to balance your system.
Isn't there a problem with low temperature hor water. I was under the impression that hot water for taos etc should be at a minimum of 50 c to kill virus and bacteria throwing !
3 years ago I had a boiler failure so needed a replacement next day. Went for BOX but had no time to do a survey of house and radiators. They provided greenstar 30i with Google next.
I found out later that nest is not compatible with bosh Worcester controls so only does on/off.
Most of house had been plumbed with 8mm micro bore but I replaced downstairs with 15mm and installed smaller but double, finned radiators. Much better heating than 3xs longer one but then realised boiler set to 80deg.
Tried 50 Deg but not heating rooms to 20.
From tomorrow I'll do a full survey.
Thinking talking to Bosch about modulating controlls. If not scrap it and go for heat only and elec instantaneous heaters on the 2 sinks. 2.5 kw instead of 26 kw from gas boiler plus time and heat wasted until water runs hot.
Comments please?
So you want to spend £3000 to save less than £100 per year. Why?
@@markjones1337 I'm hoping to save much more than that with updated controls. Just annoyed that Boxt supplied the simplest on/off control system rather than the best modulating one available.
@@Michael.Huxley I'm a heating engineer. When Boiler Plus came out a few years ago (April 2018 I think) I saw some of the figures quoted at the time, not one quoted more than £25 per year saving, that was a flue gas recovery system which cost about £700.
You will not save any money, the outlay always takes 10 to 25 years to pay for itself.
In reply to your 26kw vs 2.5kw. The isn't using 26kw that's it's max, but rarely if ever will it run at max.
@@Michael.Huxley as for replaceing your rads for smaller ones, unless the the rads have been correctly sized to each room your boiler will now have to run for longer to get the house upto temperature and will spend less time in condensating mode. The longer the boiler runs the more gas you use.
Seriously, stop wasting £100s to try and save a couple of quid.
I personally dont see a need for hot water storage in modern homes. when most of the time we use very little hot water. Hot water on demand that a combi gives i think is more cost effective.
For example My gas bill in summer my daily standing charges were more then the gas i used. before i had a combi it was much much more, having to wait an hour to heat a tank up, just to fill a sink up isnt good enough for a modern home.
Horses for courses. I have a small fast recovery cylinder that heats up for 20 minutes twice a day. It also airs my towels and runs a small drying room. If the boiler breaks I just switch on the immersion heater for hot water. With a combi you've suddenly got a panic on your hands.." You've got to fix it now cos I've got a baby and I can't do without hot water" etc etc. Give me a system with a backup any day of the week 👍
@@timhancock6626 having had both systems I get both have benefits and draw backs. 🙂 But with the costs of energy heating water I won't use isn't cost effective for me.
@@sparkmeister4706 I'm a retired gas engineer. Combis have their place and I've owned a few. but I don't place them on a pedestal as being anything special as they give the most trouble by far. Given a free choice i'd go for a system boiler with unvented hot water. I don't change my heat only as the cost of changing isn't worth it for the small improvements i'd get.
@@timhancock6626 that's fine in your experience.
My heat only from new got condemned at 6 year old. It constantly failed and broke down from new.
My ideal vogue combination has been fault free from 2018 when installed.
I ripped out an old back boiler system. Never looked back. £7 a month on gas during summer. Usage less than the standing charges !
I think it's all subjective. Large family with multiple kids etc. Then yeah a storage tank is great as hot water used all day.
For me/us where hot water is only used for the shower. And occasionally the sink. It's just not worth heating it up
You cant have a pumped shower with a combi and if you live in a low water pressure area like I do, you need a pump if you want a decent shower. Ergo, you need a hot water tank.
Very knowledgable, but I still don't know how to add the mystery device to my combi boiler.
At the end should be accept not except
Perhaps the Government should insist upon water companies providing warmer water in the mains! This would create far less need for heating in the home, and have an immediate impact upon the emissions. This could be achieved in many ways like covered reservoirs - high installation cost but long term advantages! Maybe installing water mains at below 2.5m would take advantage of the geo- thermal ground temperature of 52 degrees(?) Warmer water into the home would be to the long term good of the planet- or would it?
Loved the videos and applied simplified checks that anyone can do! Thank you!
I am moving house soon and need a total review o the systems in the new house, which is beyond my comprehension!
The General public are unaware of anything like this tutorial, and are at the mercy of the installers recommendation! I have never had any explanation of the pros and cons of the various boilers, or suggested settings described! I recently had a complete new Combi Central heating system, with new convection radiators, and have not yet even set the programmer! I just turn it on as needed!
Ariston One boiler, 6 rads, and a lot of mess! Total charge £9,000 ! Seems a lot of money given the advice in your tutorial!
Having completed the new installation we then found our dream home elsewhere, and now need to look into the whole system for the Bungalow!
👍👍👍👍👍
I find a 26kw combi the perfect size
The perfect size for what??????........
🤘😎🤘🇬🇧
What a waste of time.
The problem for customers, who have had a boiler 'mis-installed/poorly commisioned', is that to call out an engineer to range rate the boiler, it will cost you £150 just to get them through the door, thus negating a couple of years savings. The 80% of 80% of 80% should now be suing their installers for not doing the job properly in the first place. On another note, great content, presented well and ultimately illuminating. Quick question....after range rating a WB system 30KW CDI, (all button controlled) must you then re run a telegan flue analysis?
Why don't al boilers have the ability to drop the kw output . Most of the time the boiler is cycling .
Priority hot water is the best way to go for heat only and system .
Most installers I talk to don't seem to be interested .
Stupid question how to restrict my water down to 9 litres per minute plz.
Either the ball valve on the pipe just under the tap or the main isolation valve on the boiler.
I along with many others have suddenly started to take an interest in the white box in the corner, so these videos are very useful. The only problem I have is a 30kW boiler that is only six years old. If I had taken the trouble to investigate this type of information before it was fitted, I would have gone for a smaller, cheaper boiler. Marketing is a very powerful tool. Look forward to the video regarding weather compensation.
At the heart of this debate is ultimately the flow rate available.
Lowering the hot water set point to as close to point of use temperature as possible is a must, but bear in mind the mains temperature in winter will likely be around 10C lower, which is why historically, I've specified 28kw/30kw to maintain similar flow/temperatures summer and winter.May have to modify this view.
@@johnward5006 I’ve set my flow temp at 50 degrees both on hot water and heating, do you think I’ll have to raise that them come December?
Check the boiler settings you can probably reduce the output on your boiler in heating and hot water if a combi.
@@simonstones1918 Very good question, it depends on output of combi, in simple terms to maintain the same flow and temperature summer and winter, the combi needs spare capacity at design stage, if so the answer for hot water is no, the boiler will respond.
With regard to heating,it's dependent on heat loss of the building given ambient temperature.
Typically and historically my advice was always pre condensing high boiler temperature = high rad output = high heat transfer.
But with the advent of condensing boilers, keep boiler set temperature at 55 until ambient temperature drops and you feel warm up is slowing, then raise boiler temperature say 5C in stages. It's not a wonderful solution, but boiler open therm/ with weather compensation, combined with operating comfort and set back temperatures will take the trial and error out of the equation.
Sorry for dragging it out ,but answer to your question is both simple and not so simple! Basically, if your feeling cold ,put a thicker jumper on; last resort is turn the boiler up.
Come the cold weather, I hope I take my own advice!
@@johnward5006 well I’m setting my boiler at 50 degrees for both options and will only up the temp if it’s needed. Can I add weather comp to my Ideal logic 5 year old boiler?
Who cares if it struggled to modulate if its using (16.27 14.65) / 16.27 = 10% LESS gas?
This was addressed in the video, accurate temperature and not cycling the boiler on and off a lot more which affects reliability
@@martinwright7367 this video (as defined in the title) is about savings gas. Its not about reducing the number of time a relay opens or closes!
@@kevinleesmith ok you want to save gas but don't care if boiler can't get temperature right and breaks down good for you
@@martinwright7367 strawman argument. just because the boiler is cycling does not mean its going to breakdown. I am pretty sure any boiler is designed to turn on and off a billion times. Anyway, you are moving away from then point which is this video is about saving gas.
If you watch more videos from this channel you will see that boilers cycling more than they should is directly linked to reliability and efficiency. It's not just a relay clicking. No they are not designed for unlimited cycles no machine ever is
4 Bed Semi with Navien 37kw 500NCB combi boiler fitted, max hot water flow rate is 15 LPM, Hot water temp set at 45 degrees, 2 minutes hot water with digital thermometer 46 degrees, 1.7801 kwh used in 2 minutes
Very right Derek but again it is down to these paper and plastic gaa engineers that actually only know what they are fed to believe, or know the best priced boiler against the easiest to fit, if it works or not, to make as much money as they can. The ratio of temperature output to temperature return to them has nothing to do with it as it is not marked on the box. Throw a few thermostatic rad valves in just to complete the non-working condensing boiler circuit. Which as a role the circuit itself is bought as a pack, as in an 8 roomed house you need an 8 rad pack, to fit them where they fit, which has nothing at all to do with a condensing circuit and very few would have any knowledge about that or how to design one. That is for new builds as of course older existing systems were never designed for condensing boilers to work as they should. As you know it is more the ink is still wet on the Gas Safe plastic so whack them in boys as we will be on doctors money in a few weeks.
Save yourself alot of money and find a Viessmann installer to fit a Viessmann 200-W. No other boiler is as efficient with such a low modulation ratio!
Viessmann maybe the boiler of choice because of modulation ratio. However the installation and setup is only as good as the person doing the job. And how installers take the time and trouble to carry out heat loss valuations, take the time to properly power flush and then balance the system. Never mind everything else. 🙄
@@RayMondElec Agree - its essential to get a Viessmann recommended installer, one with an excellent reputation.
@@RayMondElec Totally agree , been Viessmann trained since 2009.
Recommend Viessmann system and compact range, but Intergas for combis, my boiler at home is a Rapid 32 with open therm/ weather compensation.
Yes I would definitely recommend a viessmann combination boiler even 100 series can modulate down to 1.9 KW
@@SalimKhan-gk1fh I don't believe it can. I believe it's slightly higher at 3kW
Great video thanks. I'm considering adding a smart thermostat to my home which do weather compensation via the internet, do you think that is a good approach or should I hardwire a dedicated outdoor sensor?
Wow I learned so much from your vid many thanks! Got some good questions to ask the companies quoting for my boiler replacement!
I’m hoping to keep my combi condensing longer this year by having a very reduced CH flow temperature so my return temp should be much lower.
Viessmann boilers can be range rated down to less than 3kW. Intergas come close too
Very interesting video..Thank you Derek
I hit the like button 983 times 👍
Derek my boiler heats my hot water in a cylinder and heats my radiators is this a ‘system boiler’ ? What would be the most efficient flow temperature I should set the boiler at? as at the moment I’ve set it quite high and I do not get the ‘plume’ I see on other condensing boiler exhausts . Is this due to the return temperature being higher than the condensing temperature of 50 degrees C that I think you mentioned regards
If you have to pressurize your boiler it is most likely it is a 'system' boiler. The other way to tell is...where is the pump? If its an external pump on the pipework you almost certainly have a heat only boiler. A system boiler has it inside the boiler casing and the pump is part of the boiler. Although not comprehensive advice i'd suggest you try turning down your boiler stat (not the roomstat) a little at a time for a day or two and see how you get on, then turn it down a bit more...until you decide its no longer heating your house, then turn it up a touch. Other than that, if you have a gas engineer who services your boiler ask him when he next visits what steps you can take to maximise boiler efficiency. They should be able to make helpful suggestions, or speak to the Customer Services division of your boiler manufacturer. If anybody knows the boiler, they should and they will be able to tell you if there are additional boiler controls that could improve efficiency.
If my taps allow way too much flow, then, would it help if I restricted the water supply to the boiler? Just a thought.
Easier to just not turn your tap on as much.
Derek a great set of videos , however i have range rated my Worcester Bosch Greenstar boiler down to 8.2kw , reduced my ch temp to 62 , the return temp sits at 54. this is the first time the boiler has actually been condensing however a fault code EF 349 The boiler’s operation is at a minimum burner load has shown up , is this something to worry about ?
Have you got enough water in your system
@@tomkatgastraining it was over 1 bar , just topped it up to 11/4 bar ,range rate upto 10kw however
the record of the fault is still sitting in the info menu of last fault recorded , how do i know if this has worked ?
@@ChrisB-ms1iq wait and see if it does it again
My vissanman 100w can modulate down to 8%.
I don’t think so. The latest version can reach a ratio 0f 10:1 which is 10% the previous version was 8:1 which is 12.5% so I think you are possibly misunderstanding the ratio versus percentage.
@@chrishard7616 its showing 8% in the app?
Good video as usual Derek. However, one point! The 70kw maximum for domestic engineers usually applies to an individual appliance, not the aggregated total for the number of appliances in the property, unless they are in the same room. For example 2 boilers linked together. The size of the gas installation is the governing factor.
Sorry mate it isn’t it’s 70kw total in one property or a maximum of 16m3 for a meter a maximum pipe size of 35mm and an installation volume of 0.035 m3 total
He's correct, it's the total load with diversity factors taken into consideration if appropriate.Whether the appliances are in the same room or not has no bearing on the subject.
@@tomkatgastraining I've just had a similar conversation!
@@tomkatgastraining
Thank for this Derek. I had this conversation
with GSR a few years back. I was quoting for a large property. They'd just had a garden building built with a bar, small gym and guest bedroom with kitchenette, (Lucky. .....) Same meter, inch and a quarter steel installation pipe to be extended to garden building. They wanted a separate combi installed in the new build which pushed the combined total over 70kw
GSR told me as long as the installation pipework and meter are within domestic scope and no single appliance exceeded 70kw nett it was fine. Exception would be if the 2 boilers were in the same room. That would be classed as a commercial plant-room.
Since your reply to my comment, I've checked to see if things have changed since I quoted for the work. I found a Q&A article (Oct 21) in GSR's Gas Engineer mag which seems to confirm this is still the case!
@@tonyadams380 it’s all about if you are carrying out a tightness test or not
I just had fitted a 32kW Ideal Vogue combi. The water flow from my tap dictated the boiler size so the boiler is over sized for my 12 radiators even allowing for modulation and the lower output for heating. If the heating is run at a lower temperature is that doing the same as range rating as my boiler can’t be range rated?
Fit weather comp and a load compensating room stat if you haven’t already. It will help massively.
If combi boiler does or can heat hot water and heating at the same time? Is it cheaper to take bath/shower at the same time when combi boiler is on?
Combi boilers can only do heating or hot water they can’t do both at the same time
@@tomkatgastraining Crap! Three months ago we replaced old back boiler with new combi boiler as per plumber's advice. He said combi boiler will heat water and heating, but now it seems that it can't heat both at the same time. And because of this it will use twice as more gas over the heating season?
With rising gas prices now it feels we made the wrong decision based on the poor plumber's advice.
What type of boiler can heat water and heating at the same time? And how it compares on gas usage comparing to combi boiler?
@@tomasbilza2783 a combi boiler is a lot more efficient than your back boiler if it’s been set up correctly. Even though it heats the heating and water separately you only heat the water you use not like you did with your back boiler which heated a cylinder. I don’t know what you are referring to with the crap at the beginning but you shouldn’t use more gas with a combi compared to a back boiler and you haven’t been miss informed by your gas engineer.
@@tomkatgastraining Thanks for your informative answer.
I thought new system boiler would suit better and use less gas compare to new combi boiler because it heats hot water and heating at the same time using same amount of gas. Or is this wrong assumption?
@@tomasbilza2783 correct and incorrect it’s all about the kw consumption and how long it runs for a system boiler would use more gas in most cases than a combi because of the water volume of the cylinder