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Just ordered a heat pump water heater yesterday. According to the sales info it should pay for itself in 4 years due to reduced electrical costs. I don't know how accurate that is since our domestic hot water is currently NG using an on-demand heater. Anywho, my main motivation is to disconnect the gas line to the house. That will certainly make it economical since we pay nearly $40/month just in 'fees' to be connected to the gas line.

We currently have gas for domestic hot water and house heating (same unit) and the dryer. I have an electric dryer ready to install but need to find space for it in the basement, do the wiring and ducting, etc etc. The last piece of the puzzle will be house heat. For that I'm planning to do some sort of air-source heat pumps but I think that might be beyond my DIY capabilities. I'll update later when the water heater is installed. Hopefully it will get done by EOY but no guarantees :lol:
 
Don't forget GB that the heat pump HW heater essentially cannibalizes heat from whatever room it is in, so..... don't put it in a bathroom, bedroom not great because they make noise when running,.... basements are the best because the basement will be heated at least partially from the Earth and probably partially by unused heat from the heating system. The heat pump will cool off whatever room it is in by the same number of BTUs that are used to heat the water (well, efficiency aside...) There is no FREE lunch.....
 
Speaking of half-assed ground sourcing: when I connect the portable heat pump in the dining room, with the exhaust out that window, I figure that the air coming in to replace the cold exhausted air is mainly coming in through the foundation, and being warmed by the cellar, which is in turn warmed by the ground... I may even try to rig a conduit to bring up cellar air more directly.

On a darker note, I've been looking for an air source heat pump that is affordable for us (my housemate has veto power over spending, and she's fairly Cheap) and that will directly replace the 13.0 EER central A/C unit on the North wall of the house, sending heat as well as cold to the A coil in the furnace. The two units were sold and installed as a pair, and the furnace manufacturer says that while they no longer sell heat pumps, what I suggest is quite possible. The Interweb as a whole, however, says:

No.
NO.
NO!
NO, NO, NO!
Yes. Maybe.

I'm not looking for super high efficiency at a price of $5k. I want to avoid running the oil furnace when temps are above about 20F. Opinions? Suggestions? The local installers take a $3k heat pump, install it, and charge $8500, although that, presumable, is with a new, matched air handler. I want to take a $3k heat pump, and have it connected to the same lines that currently carry refrigerant for the central A/C. The A/C unit is rated at, depending on which sub-model it is, between 29,000 and 36,000 BTUs. Does that limit me to a 36k BTU heat pump, or can I go higher?
 
The water heater is going in an unfinished but partially insulated basement. I am a bit concerned about cooling it in the winter since the house's forced air blower is also down there. (there is a heating coil inside the ducts that replaced the old NG burner).

The unit I bought claims that both the inlet and outlet air streams can be ducted. I have a convenient run to the attic in the chase that held the flue for the old gas furnace exhaust so I'm planning to duct both the inlet and outlet to the attic. I figure I can get hot air from the attic and cool it at the same time, so yes....a free lunch! However, the water heater inlet air temp is supposed to be < 145F. I don't know how hot my attic gets in the summer but I wouldn't be surprised if it exceeds that sometimes. So I might have to pull inlet air from the basement in the summer or maybe I can schedule the water heater to not run during the afternoons in the summer. I won't know until next year how much I need to worry about this but I'm confident I can figure something out. Also, I'm hoping putting the cool exhaust air into the attic will help keep the temps down. The attic is also now shaded by solar panels but I don't know how much that will help.
 
Sounds like you have this all figured..... and if your DHW heater is like the ones we use it can be set to run pure heat pump, hybrid or pure electric so if there are any issues it still works... hard to imagine even air hotter than 145F coming down a duct and not cooling off enough to be safe for the unit.
 
I hope so. It sure seems like it will work and this unit also has electric backup just in case. It's pretty fancy (Rheem Performance Platinum) so I imagine it will do everything I need. My biggest concern is getting the util company to disconnect the gas line. I assume they will do that but I doubt it will be free or cheap.
 
LeftieBiker said:
Speaking of half-assed ground sourcing: when I connect the portable heat pump in the dining room, with the exhaust out that window, I figure that the air coming in to replace the cold exhausted air is mainly coming in through the foundation, and being warmed by the cellar, which is in turn warmed by the ground... I may even try to rig a conduit to bring up cellar air more directly.

On a darker note, I've been looking for an air source heat pump that is affordable for us (my housemate has veto power over spending, and she's fairly Cheap) and that will directly replace the 13.0 EER central A/C unit on the North wall of the house, sending heat as well as cold to the A coil in the furnace. The two units were sold and installed as a pair, and the furnace manufacturer says that while they no longer sell heat pumps, what I suggest is quite possible. The Interweb as a whole, however, says:

No.
NO.
NO!
NO, NO, NO!
Yes. Maybe.

I'm not looking for super high efficiency at a price of $5k. I want to avoid running the oil furnace when temps are above about 20F. Opinions? Suggestions? The local installers take a $3k heat pump, install it, and charge $8500, although that, presumable, is with a new, matched air handler. I want to take a $3k heat pump, and have it connected to the same lines that currently carry refrigerant for the central A/C. The A/C unit is rated at, depending on which sub-model it is, between 29,000 and 36,000 BTUs. Does that limit me to a 36k BTU heat pump, or can I go higher?

Well if you read some of my posts (other thread) I had good luck with the Mr. cool brand, their quirky adds aside. I can't tell you anything on longevity though. But the price was right. A full five ton heat pump system and pre-charged lines for less than 4k. Installed myself.
so if you have an old split system - outside compressor, inside or attic blower, that could be a nearly drop in replacement. but you would need to pull their new lines they provide. All pre-charged. Now if you don't want a full split system, they also sell DIY mini splits. Costco sells those as kits and they are cheap and come with their own pre-charged line sets. I may do one of those for my garage.

If you want I can provide you a link to the unit I bought, if you can't find the thread I did.

As far as your BTUs, you need to go with the unit the hits your target for either higher AC or heat pump loads. Probably heat pump for you? Then your AC will run for less time. You don't want to overly short cycle, but even a professionally installed unit has the same issue, they only install for the max load. Sure they have fancy tech like multi stage compressors and such, but the max tonnage is the same.

Your one wrinkle is that it sounds like you would keep your oil furnace? So you would have an A coil on top of your furnace, and the furnace has the blower? Maybe I'm reading that wrong.
 
Yes, furnace with A coil. I want to make sure that I can go with, say, 48kbtu and have it work with the 29-36k btu A/C system components that will remain in place. That means going with non-pre-charged lines, because they have to be connected to the A coil.

MR. Cool is the brand mini split that I installed myself a couple of years ago. I'm unhappy with the way it lets the temperature wander up to 4 degrees, but it's been reliable.
 
LeftieBiker said:
Yes, furnace with A coil. I want to make sure that I can go with, say, 48kbtu and have it work with the 29-36k btu A/C system components that will remain in place. That means going with non-pre-charged lines, because they have to be connected to the A coil.

MR. Cool is the brand mini split that I installed myself a couple of years ago. I'm unhappy with the way it lets the temperature wander up to 4 degrees, but it's been reliable.

So for mine, because its whole house, I used a Honeywell T10 thermostat. So I can't comment on the Mr. Cool thermostat that comes with their mini splits. (No thermostat is included with the whole house units) I will say the T10 is quite good, with a huge variety of setup options. High tech but not shout in your face like a nest.

So for your unique situation I think they do sell the individual components, and then you need to get an installer in to do the vacuuming of the lines and weighing in the refrigerant. I know they even sell an A coil kit, but when I checked, it was AC only. They may have some other options though, as they had more than one "brand". I used the Mr. Cool Universal... so you might want their Signature line or another.

Check out Ingram's Water and Air. They can give you good advice even if you don't buy through them.
https://iwae.com/shop/heating-air-conditioning/
 
Thanks. I just posted my question there, about one of the Mr. Cool standalone heatpump units. Trying to get an estimate for a sub-$8k job is not easy. I mostly get calls from people wanting to sell me more expensive, complete systems.
 
LeftieBiker said:
I've been looking for an air source heat pump that is affordable for us ... and that will directly replace the 13.0 EER central A/C unit on the North wall of the house, sending heat as well as cold to the A coil in the furnace. The two units were sold and installed as a pair, and the furnace manufacturer says that while they no longer sell heat pumps, what I suggest is quite possible.

I am researching a similar idea to make a split heat pump heater for DHW and also my spa, both which are now NG. according to one single youtuber guy who made his own split DHW tank claims that the indoor unit is nothing more than a length of pipe. So a plate/plate exchanger or your A coil would not be different. Two cravats, a traditional AC unit might have an expansion valve right at the evaporator, so that would need to be bypassed as the split system heat pumps have all that inside the outdoor unit. also he used the indoor unit in his install, using just the outdoor unit by itself would require a hacker-level control system with a thermostat ( a quick google seems to indicate that the indoor unit communicates with the outdoor unit via a pulse modulation signal on the single non-power wire that connects the two units) The big upside is there are 24-36Kbtu outdoor units from mini-splits by themselves for only a few hundred out there.

https://www.youtube.com/watch?v=g5y-_Axl284
 
That sounds like some creative wiring and programming is required. I was hoping that I could find an outdoor unit that doesn't have a linked air handler inside the house. The ones I was directed to in the above post seem to be of the latter type.

Because all of the mini-splits coming out in the last few years have been designed for max efficiency and for working in colder temperatures, and because the 2 components (indoor and outdoor) need to work together, I will be surprised if you will find a stand-alone unit or if you do if anyone will be willing to hook up the tubing. Best of luck..... my son has 2 outdoor units sitting in his driveway, taken out of building projects, and has not been able to find indoor units to match them correctly. (maybe you and he need to talk....)
 
The problem is that my housemate isn't going to go for a $9k project in which we have people working inside the house for days, taking apart half of the furnace (which we will be needing any day now) and exceeding their estimate by thousands of dollars. The only ways I can get a heat pump this year are either by doing what I propose above, or by doing another mini-split install - this time with 3 or 4 air handlers. I barely managed the last one with one air handler, and I'm much more feeble now. It's looking like I'll just be hooking up the portable heat pump in the dining room, and running that very loud piece of...technology when it won't disturb us. I really hate that we're still burning fuel oil (she is terrified of gas furnaces) in 2021, as the world begins to burn.
 
We finally installed an on-demand propane boiler (a combi, does DHW also) after heating solely with wood for fifty years. It only runs for a brief period in the AM 'till we get the fires going.... It is elegant and efficient but still burns stuff that should be left in the ground. Not entirely sure that mini-splits are that much better......
 
I think that mini splits are a bit like EVs: they have enough embodied pollution that you have to run them for a few years to "break even" on pollutants, but they do reduce the pollution in the locale in which they are used.
 
LeftieBiker said:
The problem is that my housemate isn't going to go for a $9k project in which we have people working inside the house for days, taking apart half of the furnace (which we will be needing any day now) and exceeding their estimate by thousands of dollars. The only ways I can get a heat pump this year are either by doing what I propose above, or by doing another mini-split install - this time with 3 or 4 air handlers. I barely managed the last one with one air handler, and I'm much more feeble now. It's looking like I'll just be hooking up the portable heat pump in the dining room, and running that very loud piece of...technology when it won't disturb us. I really hate that we're still burning fuel oil (she is terrified of gas furnaces) in 2021, as the world begins to burn.

I'm not really an expert (just play one here) and had to learn as I went on my project, but I really do think you would need a new furnace and A coil and outside unit. But you should be able to keep your old lines, though its possible pulling bigger or new properly sized lines would be more efficient. And they would need vacuuming and refrigerant weighed in.

Excluding some really crazy janky stuff, a new forced air furnace (you want NG? Or keep Oil?) would likely be needed, and that acts as the blower. If I recall correctly, when you have the furnace acting as the blower, the A coil must go above (up stream) AND they can't both run at the same time in heating mode, because the furnace is too hot, and trying to run the furnace and the A Coil (in heat pump mode) is too hot for the coil. Which is a bit disappointing because the coil still produces heat, just diminishing returns as it gets colder outside. With an all electric setup you CAN run both the heat pump and the emergency heat - but that is because first the heat pump heats the air through the coil (which is BEFORE the blower) and then the warm air is then heated more by the electric heat strip kit. So that is an important difference - in your setup you PUSH the air through the coil. In mine, the air is pulled through the coil first. Just something to remember.

But can you technically keep your old oil furnace, replace the A coil and outside condenser? I think so. Most furnaces have a blower speed setting and you might need to adjust it. A new oil furnace on its own is probably 2-3k? I actually looked at this route for myself - replacing my NG furnace, adding the A coil on top and condenser outside. But it added substantial cost because now I had to get a new furnace AND the A-coil and condenser kit. Plus the DIY pre-charged line kits were only compatible with the AC ONLY A coil/condenser kit (or the full heat pump kit, but no NG furnace), and I wanted a heat pump. Add in that I realized when the NG furnace was running the heat pump was forced off, and I decided to go all electric. We don't get that cold anyway, so the heat strip will likely never run. I installed it basically as a backup in case my heat pump ever dies. That all sounds a bit confusing, sorry. In other words the DIY kits (when I got it) was AC and furnace, or Heatpump only. But if you don't want to go DIY, there must be a A-coil and Heatpump setup using your old furnace as the blower.

Not sure any of this helped, but good luck!
 
I'm just following along since I'm trying to decide how to upgrade my system as well.

First, I have a question: what's an A coil?

Second, I imagine just about any forced air system has a switch on the thermostat to just run the blower with no heat or AC used. I know mine does that and I'd guess just about any system will. Not automatic by any means but using the furnace blower without (oil) heat should be easy.
 
It should be, but isn't. The units I was considering are not compatible for what I wanted to do, according to the HVAC business above, as they are designed as self-contained systems.

An A coil is a heat exchanger coil that is installed in the furnace air plenum. It is connected to lines from a central A/C unit. It may be possible to do what I want, but I'm not going to find anyone to do it. I'm likely looking at the nightmare of having a mini split installed with multiple air handlers, or at having a $10k heat pump system installed parallel to the furnace or replacing it with backup heating strips. That means another Winter of oil heat and about six electric heaters.
 
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