“Dual Fuel Heat Pumps are JUNK” 😬🔥
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- Опубликовано: 26 сен 2024
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In this video we're going to talk about why dual fuel heat pumps are a good option for moderate to colder climates, we'll respond to one of our subscribers comments that stated "dual fuel heat pumps are junk" and we'll debunk why that statement is furthest from the truth.
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This is my fourth upper midwest winter with a Daikin Fit. It handles 75% of my heating load in winter. The coldest stretch of winter is handled by my Daikin gas furnace. It is a great set-up and we enjoy the comfort and even heat that the heat pump provides. We definitely notice a difference between the two heat sources and prefer the heat pump. We used this setup because the home was built in the 90's and needs some insulation and duct re-working to be a candidate for a 100% ASHP; which we definitely plan to do.
A year ago I had a Mitsubishi duel fuel intel-Heat system installed here in Wisconsin. Last winter the system would rely on my 15 year old Lennox natural gas furnace whenever it got below 30 degrees. Fast forward to this winter and I’m not sure what has changed but the system has been heating my home the whole time. It has been a very mild winter so far but even on the morning where it got down to 11 degrees a few weeks ago the furnace never came on. Even when my hvac contractor came to do maintenance on my furnace he has to disable the Mitsubishi system so that it would kick over to only run the furnace while he worked on it.
You are right about feeling the difference between the two heat sources. Last year I could tell when the furnace was running and when the heat pump was running. I was complaining to the hvac salesman that I was disappointed that my heat pump was not working to the advertised 5 degrees and he said, “well how can you tell”, I stated that without even looking I could tell the difference. I think he thought I was wrong but I can.
Right on that’s great to hear!
@@jko0526 down to 5 degrees are the hyper heat models, is that what you have? Also, i believe it was rated based on ductless head units and not ducted as you’re losing temperature when air moves thru ducts.
I installed a 12000 btu single zone hyper heat ductless for my addition,and it was pumping out like 100F+ when it was 10F outdoor ambient temperature. My main-heatpump system was struggling.
The biggest variable it comes down to utilities costing. If i am going to invest in a dual fuel heat pump I want to save money on utilities costs but the initial cost of a dual fuel heat pump is bigger than a conventional system
It depends a lot on the relative prices of natural gas vs electric in a given location. In some areas gas costs a lot less per unit of energy than electric does. Given the over-efficiency of modern heat pumps at not-as-cold temperatures, it might make perfect sense to use the HP down to a certain point, and then switch over to gas. And higher end thermostats support doing exactly that (or sometimes such installations, a control board in the system itself does that)
Very true, we’re normally setting switchover temps here between 10-20F depending on whether or not they have solar because that is a big offset for a lot of people
Spacepak Solstice is a nice unit and readily available here. Excellent video, So few understand about the different heating and cooling loads across the country and you did an excellent job explaining it.
Thanks appreciate that, and yes I’ve seen these they look like nice units. Got a quote on one the other day for a customer we were trying to get them some information on them for their application.
Great videos.
I’m a huge fan of R-290 but there are a variety of cold-climate capable air-to-water heat pumps you can use today: Chiltrix, SpacePak, Enertech (harder to get), Aermec, Viessmann.. Daikin make great stuff but don’t get hung up on them being behind the curve and get into AWHPs now. I’ve been specifying them for 8-9 years now and bought a Chiltrix CX-50 for my house. Time to catch up with how to do better than dual fuel and no need to size heat pumps to cooling load!!!
Good to know, I’ll check them out! Been wondering where to get them / who makes them… Sizing heat pumps to the cooling load is mostly pertinent on single stage equipment for us but it sounds like the R290 stuff doesn’t have those same limitations. Just don’t want things oversized for the ductwork and also short cycling
10 years with a Mitsubishi air to water heater in Sweden. It works down to -13F although it has run lower too and still produced heat although a little less heat then.
It also creates all our tap water. Natural gas is exotic here, you can buy imported gas in canisters for your BBQ.
Burning gas unsupervised does not seem wise. I'd stick with the electric one. ;)
Yeah they work great we love them!
Look at Spacepak AWHPs. But best for low temperature systems. You'll most likely need to upgrade any existing heat emitters.
Will check them out thanks!
Can you do a video on simultaneous heating and cooling in a residential setting?
Two story homes often need ac upstairs and heat downstairs during shoulder seasons/shoulder hours.
Moving the heat generated by air conditioning the upstairs and using it to warm the downstairs is a much more economical way to solve the problem than is running a furnace downstairs and an ac upstairs-you’re paying twice to condition your house.
I know the commercial heat pumps have this feature but I don’t see it on the residential ones. Why not? Can I just install the commercial one in my house?
I believe you’re referring to heat recovery VRF. I don’t believe they make them for residential. I suppose if you had a huge house you could but all of the compressors I have seen are 3 phase 480 Volt. So that would be a problem too in a residential environment. But I would not be too surprised if they do come out with a residential one some day. I think the main reason they have not is the very large cost of it.
Good answer: “heat recovery” variable refrigerant flow (VRF) exists in 3-ph, not single phase and it would not be an efficient solution for your situation in any case or not enough to justify the complexity and expense: get floor by floor heat pumps for the probably more rare than you think situation. Alternatively, you could invest less money in solving the “stack effect” problem and thoroughly air sealing your house and upper floor in particular. The most likely reason you are overheating your lower level and wanting to cool off your upper level is that, lhot air is rising to make up for loss of heated air upstairs. If your house were less drafty, you have less convected air accumulating upstairs and cold air infiltrating downstairs ( note: heat does not “rise”, heated air does)
I have this problem daily for several hours in the spring and fall mornings. The third floor has a lot of south facing roof and the house has no wall insulation but it’s stucco siding.
The result is the sun takes a lot longer to warm the downstairs than the upstairs, meaning the downstairs thermostat is still calling for heat while the upstairs thermostat is calling for air conditioning.
I already have a separate ac for the third floor.
I just don’t feel like paying for natural gas to heat the downstairs while at the same time paying for electricity to cool the third floor. The waste heat from cooling the upstairs is enough to heat the downstairs if only I had a means by which to move the heat.
Try running your fan to circulate the air but these commenters hit the nail on the head. 3 pipe VRF heat recovery can do this but it’s all 3 phase power and not cost effective at all. They use these in hotels and things like that where they can pass heat energy from roof to room through the refrigerant, awesome tech but not for residential
Fan circulation
Hello, I'm curious if there are any dual source air handlers on the market? I'm from northern Alberta Canada and although I'm entirely convinced Heat Pumps are the future when you pair poorly insulated buildings with an annual shot of
So what you’re looking for is an air to water air handler or forced air hydronics air handler. Yes they exist for a lot of condo applications they’re made by Firstco but there’s other brands out there as well with water coils
For example rinnai makes a hydronic air handler but idk if that also has a coil for ac
www.rheem.com/innovations/innovation_residential/integrated_systems/
enertechusa.com/products/enertech-air-handlers/hydronic
For example with the Enertech system, it is an air to water heat pump, and you could probably set it up with a relay based on outdoor temps, and a zone valve and pump so that on the coldest nights your boiler kicks into to heat the water loop. Will look into this more great topic
I have gas heating, but recently installed a 1ton heat pump as supplementary heating for my living room. I live in Oklahoma and one situation I realized that I would not be able to use my heatpump is during ice storms, which are not uncommon in Oklahoma. The ice would coat the outdoor unit and make it impossible to use. So while I am quite impressed with the performance of the heat pump for heating and saving on propane usage, I do not see giving up gas heating as an option for me.
Is there no defrost option on your outdoor unit? It may have an option in your controller panel. Just hit it and you can use it all the time.
@@bdblazer6400 The unit I have can deice the coils, but it can't deice the fan blades.
Horizontal flow heat pumps do not have this issue of functionally exposed fan blades. You may want to consider upgrading your heat pump in the future to an air to water heat pump and hydronic coil over your furnace for cooling and also winter heating - they are all side discharge and you should have a little shed roof over any heat pump ideally in any case but that’s just me.
Most of the units have snow / ice guards you can buy as an addon or hail guards. We’ve had these put on systems that were very exposed to hail
Great video like all of your others.
Relating to duel fuel with a gas furnace.
Do all heat pumps go into defrost? Even the inverter type?
If so is there supposed to be a wire to run the gas furnace while in defrost?
I've seen some other installation videos that don't do it. It's usually on the inverter type.
I've seen a terminal labeled "D" on the HP but nothing connected.
I know they are normally not supposed to run at the same time but I read that is should in defrost so you aren't blowing cold air.
Thanks!
It depends how it’s set up, but every heat pump has a defrost cycle. As far as furnace heating every heat pump is different but when it’s paired with a furnace it’s just a matter of the settings and how it’s commissioned but normally this can be set up but we usually don’t unless the customer wants it
I've been watching all your videos very interesting. I did not know technology had come far enough to make heat pumps available where I live. I grew up with heat pumps in washington state and my engineering class thermo books all reinforced the myth they only work in warmer climates.
Right on thanks for watching! Yes a lot of new inverter heat pumps work great in cold weather, not the old heat pumps you’re used to 😁
Just have to verify the specs when you’re buying it but we have lots of cold weather heat pumps that are very efficient
I'm considering having a house built in Florida and the builder installs single stage Trane 15 SEER heat pump systems (it says with variable speed air handler). They would charge about $5K for an upgrade to a 2-stage heat pump. I really would not want either of these systems. Would I be able to replace just the outdoor condensing unit with a variable speed heat pump after moving in? What would you recommend?
I currently have a 17" wide Carrier 58SB1A furnace that was replaced in 2020. In 2022 I got solar and have since started the switch to all electric. My last gas appliance is my furnace. It sits in my HVAC closet with 17" wide doors. The problem I've run into is all 3T air handlers are 21" wide. There are some 2.5T that are 17.5" wide. One contractor came up with a solution of getting the Carrier 38MURA heat pump outdoor unit and tying it into my existing furnace. They want to convert the furnace to become an air handler only: reduce the gas line, cap it off and remove the exhaust. Then replacing the refrigerant coils above the furnace with one that will work with the 38MURA.
My question: is this method really feasible and how would using my current furnace as an air handler affect the 38MURA's efficiency/SEER2 rating? I'm not pairing the 38MURA with Carrier's recommended 40MUAA. Relocating the indoor unit to my attic would mean redoing ducts at a very high cost. The only other option is cutting the door frame of the closet to be wide enough to install an air handler, not a route I want to take if the loss in efficiency of the furnace, turn air handler, is not significant. Thank you!
Not a significant efficiency loss there’s probably an AHRI matchup isn’t there? It’s carrier paired with carrier, we do this with a lot of dual fuel applications in Colorado because if your furnace remains as backup then you’ll be in good shape if you get weather that gets below 10-20F where the heat pump might struggle more and the house insulation feels an increasing load demand too if you get really cold temps so I wouldn’t cap the furnace necessarily unless you definitely don’t need backup heat
@@TheHVACDopeShow Thanks for the reply! I live in the SF Bay Area which doesn't drop below 40 often. Another reason to cap it off is that my city is providing a $3k rebate to remove the gas furnace. They confirmed with me that capping the gas line will still qualify even though I'm not switching it out for an air handler. How does the AHRI match up work? I'm not very familiar with it. Really appreciate your videos! You discuss Daikins with such passion I wish I could get one that could fit into my closet.
Problem with these systems is that they didn't switch to backup heat automatically even thou you selected automatic setting after 32 degrees. So I will always go with complete electric or complete gas system not dual fuel systems or hybrids
12x60ft mobile home with a fully ducted oil furnace in the hottest part of bc, Canada, up to 44° in summer, -20 in winter. What would you suggest?
Mobile homes require specific furnace types for them, depends on your heating bill amount and your goals. If you’re wanting a basic system you could do Oil again and use air conditioning, or if you’re going for a heat pump you’d be able to get a mitsubishi intelliheat and that would heat year round in your climate and is the only inverter heat pump I know of that would connect to your mobile home furnace. A basic single stage heat pump wouldn’t keep up in those low temps, summer would be fine. But just depends what you’re wanting to accomplish. Thanks for the comment 😁
I’ve installed an ACIQ dual fuel unit rated for -22 degrees. It’s worked down to 9 degrees and the backup heat never called once. I’ve recently retired from heating and cooling and never had many people using heat pumps during the winter. For those wondering if they work, the answer is yes! Don’t listen to the bs from those who don’t actually use them.
Wouldn’t an inverter based system reduce the air conditioning load automatically adjust to avoid the issues that you identified?
You mean based on airflow? It will still throw an error code because it wants to ramp up based on demands but can’t because of airflow / ductwork constraints. Each system is different but you need to satisfy minimum airflow for the demands of the system
I would like your recommendation for a dual fuel ducted system for a new residential build that does not have access to natural gas due to its rural setting. The house will be a 1500 sq-ft one level ranch located in Western NY. My thoughts lean towards a standard efficacy propane furnace and Mitsubishi Intelli-heat heat pump setup, but I'm open to other options. Thanks.
I thought there's a law of physics that you cannot create or destroy energy only convert it?
Why has no one won a award for this breakthrough technology.
Not sure what you’re referencing did I say create energy lol? “Matter cannot be created or destroyed” is the quote I believe you’re referencing? Unless I’m misquoting, wouldn’t be the first time! But yeah this isn’t creating matter or energy, not sure if you’re referencing COP or what…
Does it matter in a dual fuel system whether the furnace is before or after the heat pump heat exchanger?
My understanding is the furnace is first and when it kicks on the heat pump kicks off (otherwise you’re essentially just heating the refrigerant to a higher temperature than it was when it got to the air handler, which is of course the opposite of what you’re trying to do). The result is the gas doesn’t merely pick up the slack; you get 100% gas heat the moment the heat pump is unable to maintain the set point.
While this is suboptimal from an efficiency perspective it should in theory be a relatively small fraction of your total heating days and so the environmental/cost concerns are mostly irrelevant.
Only if it’s upflow or downflow but the Evap coil is normally on top of the furnace
And yes the furnace will kick on when the heat pump is off
Thanks for your reply. I was referring to the physical relationship of the heat pump and furnace. I appreciate your podcasts, you provide a lot of useful information.
I'm in COS and just did a system replacement. I did the math heatpump and it would be WAAAAAY outside the system lifetime for ROI (which I'm told is 10-15yrs now, which is also crazy, they replaced a 40y/o unit), going from a single stage natgas furnace and SS 2 ton AC unit to a heat pump was going to double the cost and in very few circumstances is cheaper to run than the natgas furnace. So i agree you def need "dual fuel" out here, but I really don't see the point in heatpump. That money would be much better served going into new windows/weathersealing. Now we do have cheap gas here, and also our electric is natgas so there isn't any "climate" benefit for heatpumps either.....My house is small (1200sq/ft) but I'd think you would need something HUGE to justify this. I want to be clear, I went into this project thinking heatpump.... the shocker was the delta in system cost. I really don't see how a "reversing valve" ups the system price the way it does. I didn't even factor in the duckwork/blower, but I'm sure thats a thing too since the exchanger is so much cooler in a heatpump, needs more volume to make it up. What size homes do you service in denver that make the math work???? 5000+sq/ft??
It really depends on who you call because it’s normally not a massive delta and depends what you’re going for. Our customers with solar panels it’s a no brainer because they dodge their bill almost entirely for heating, but it depends which company you call. If you didn’t have any ducts though or any ductwork that would definitely make it very expensive. It’s not very cost effective because of labor costs.
What unit is that in the background? Is that a custom riser between the furnace and the coil? Is it a cold climate heatpump?
Daikin single stage system we use for training. The riser is an adapter that increases cabinet size from furnace to coil, and it’s how we teach apprentices about a clean looking install on a mismatched coil / cabinet transition (sometimes this happens with AHRI requirements for example for tonnage requirements on the indoor/outdoor combo)
I would like to replace the oil furnace with a dual fuel system but I will not get the incentive from coned if I don't get rid of the oil furnace. I am afraid to only use a heat pump because it gets cold in NY.
How much is the incentive? If it’s cold I would hold off or consider another option like geothermal if possible because you don’t want an expensive to run system just because you don’t get an incentive. Idk how much the incentive is but if your heat strips have to run as backup heat in the winter often then it will erase most your savings. If your lows stay above 0F or 5F most of the time and the heat pump keeps up with the load of the house then you’re probably ok but based on your situation and what you’re telling me I’m somewhat hesitant to recommend ditching backup dual fuel
the incentive is $10k if you get rid of gas or oil completely. $2.5k if you get a dual system.
I would not recommend putting ductwork and air handler in attic of older home in northern climate.
Why is that? For air conditioning you’ll get better heat removal, for heating I agree you’d be better with lower returns / basement system. Just often time the attic is open so we’re able to install it up there
Just found your channel and glad I did, I have a 4 ton Trane heatpump with the air-handler in the garage & all the ductwork in an unconditioned attic and the compressor outside. Where the ductwork enters the attic the rise is on an eve with the big triangular vent so attic is either very hot or very cold. To me I'm losing heat because of the cold ductwork & vise versa in summer. I'm considering air sealing the duct work and encasing it in 4 inch ridged foam. The current heat spell has caused my compressor unit to bite the dust and is past the warranty. So researching dual fuel because of a monthly $450.00 electric bill due to a very cold winter and the auxiliary heat elements provided most of the heat those month. I live in western Kentucky for reference. Currently searching for bids a quote over the phone for a Trane system was 24k, a friend suggested getting a Goodman which on line looks to be about 8k. Any suggestions or opinions. Thanks
They do suck indeed especially Goodman
I've been researching a dual fuel system and they recommended a dual fuel Goodman system. I'm wondering why you say they suck.