Talk me into (or out of) a whole house heat pump to replace dead oil boiler

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NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
406
Massachusetts
The guy I met today recommended a single zone unit from Bosch.

Bosch BVA60WN1M20 Air Handler

BOVA60HDN1M20G Condensing unit

As expected he really down played the ability of heat pumps to keep up with very cold weather and was inclined to keep the oil as a backup / no electric heating coils now, though they can be added to the unit later. Also didn't get the warm and fuzzies (or cool and fuzzies in this case) on AC performance upstairs. Flow will be lower and coming out the floor registers the air will want to sink back downstairs. Hopefully he's under-promising and over delivering...

Installed cost is 16K and that doesn't do anything for my boiler situation... I assume this single zone / no coils option is going the most bare bones so the cost isn't making me too enthusiastic - especially if there's not a great performance impact during the summer upstairs where it gets hot and muggy.

Still need to get a cost from the guy who talked about a separate handler in the attic.
 

woodgeek

Minister of Fire
Jan 27, 2008
4,373
SE PA
Huh. Seems a bit high given the (online) hardware price is only $4k.

My whole system change (with 200A box upgrade, all new ducts, and strip wiring) was about $10k in 2008.

I assume the quote is high bc of new ducting? That is, that this is not a 'drop in' replacement using the old AC ductwork (and probably wiring).

I wouldn't worry much about the AC tbh. Most installers are used to folks with unairsealed attics with a LOT of upstairs heating load.

Existing AC registers are mounted where? 50:50 upstairs and down?

In general a HP is only marginally more expensive than an AC unit of the same tonnage, for the unit. Its the wiring stuff (strips and box upgrades) that make it more expensive.
 

EbS-P

Minister of Fire
Jan 19, 2019
802
SE North Carolina
Man that price is 5k more than I was thinking. I guess if you are keeping the oil running, how much could you save with save with a 4 ton two stage American standard unit. or if you need higher efficiency to get the rebate maybe this. 18 seer American Standard 5 ton https://ashp.neep.org/#!/product/25753. Really If its rated at 41k BTUs at 5 degrees I don’t see why you would need heat strips. that Bosh unit may have better efficiency but has 6k less btus Than the AS unit At 5df. I like shopping for this kind of stuff, I hate having to make the final decision
American standard are just rebranded Trane unit. FYI.

if the rebates are still available and you can get by this summer with your current AC it might make sense to wait on this awhile. The supply chain is just so messed up right now.

my dad just did the math here for our weather and the extra money for the more efficient unit just didn’t make money sense. So he went single stage 14 seer. Your heating degree days are probably 3x our cooling degree days.

to put it in perspective I was quoted 6000$ for a single 2 ton mini split that was an easy install in a basically unfinished basement.

evan
 

velvetfoot

Minister of Fire
Dec 5, 2005
10,055
Sand Lake, NY
How much life is left in the oil boiler? My oil boiler runs as a cold start and I have a large (120 gal) indirect dhw/buffer tank, (which doubles as a buffer tank for a pellet boiler, but that's another story), on its own zone. I also have an electric and heat pump water heaters, along with the pellet boiler, but I've been only burning oil, partly because of the price of oil going down, (that's changing), laziness, noise, and ease of power outage use, as I said earlier. I'm also of the opinion, based on the observations during my own oil boiler maintenance, that keeping the boiler running for a longer time to heat that well-insulated buffer tank, is better than cycling it a lot.
 

NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
406
Massachusetts
The quote was to use existing ductwork. I wonder if there is a little bit of rebate confiscation going on. If they approved a 5 ton unit for the full rebate that’s $5,000. So they may think my budget is higher instead of letting me benefit from the rebate savings.

I think I’m going to try fixing the boiler which should be about $1,500 if it works. This would then be a replacement for my poorly running AC with the benefit of providing heat. I can run it for a few seasons to see how it does in cold weather and then when the boiler truly does die decide to upgrade to heating strips for extreme cold days, replace the boiler or upgrade the heat pump to whatever the tech is available then. Most likely it would be upgrading the electrical service and putting heating strips. Don’t forget I burn wood and plan to do that for as long as I can. Anything after the heat pump is my second backup after wood.
 
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EbS-P

Minister of Fire
Jan 19, 2019
802
SE North Carolina
So they may think my budget is higher instead of letting me benefit from the rebate savings.
I might ask for a quote on the cheapest non rebate eligible system too. I just don’t see you running the system enough to make up the cost difference between the cheap- less efficient system vs the expensive-really efficient one. It would be different if you didn’t burn wood.

Evan
 

woodgeek

Minister of Fire
Jan 27, 2008
4,373
SE PA
Makes sense. I agree about the confiscation...

I live in a HCOL area, and I find that **simple** installs usually come in at 2X the online hardware cost. That would be $8-9k in your case for a simple drop in. + $5k rebate gets to your ballpark.

Get more quotes. Or get a quote for a 4 ton AC replacement, and then up the quote to HP without any strips. It shouldn't be much more.

Ductwork for a 4 ton AC is probably a bit too small for a 5 ton HP... with a single speed compressor, running too high cfm for the ducts will make for a lot of air noise. Right sizing it will be reasonably quiet. If you existing ductwork is OK and quiet at 4 tons, it might be ok at 5. But I still think 4 tons would be enough for shoulder (>35°F with oil doing 100% of colder).

-----------------------

Oh, new idea... which I think you are already thinking...

5 tons (with current ducts up and down MIGHT be enough to cover you reasonably with strip heat backup). So you could install a 5 ton on existing ductwork with the patched boiler kicking in below 35°F. You can test it out (by playing with the tstat) to see how low it goes, and if it does OK (like down to 20°F or something), then just pull the boiler and add strips WITHOUT adding another HP.

I'll tell you two things...the 'cold blast' defrost thing is not an issue during dry weather, it is only bad when its snowing and the coil is getting packed with snow. So you could test the HP to your heart's content during dry weather and prob not even notice the defrost (the unit will defrost FINE without strips, the heat comes from conditioned house air).

I will tell you that if you DO try to run on HP only in cold weather, some rooms will get colder than others (esp with a one-zone two story setup). I ended up adding a couple branches to my ductwork over time to even that out. This has the advantage of increasing the cfm capacity of the ductwork (resolving the too small current ductwork issue).

As a woodburner, you probably don't care much about heating balance in the dead of winter anyway. The house won't freeze unattended with a 5 ton HP.

The only problem here is that a 5 ton HP might have poor dehumidification in summer AC, cool humid air is not comfortable. I'd get at least a two-speed compressor and variable speed blower to help with that, a small upcharge.
 

NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
406
Massachusetts
The current AC is pretty loud. I threw it on today and it’s a base line 60 db on a first floor room. The booster fans for upstairs are loud and rickety when they are on. All in all it’s kind of sounds like riding a subway. I often turn it off just because the sound gives me a headache. That and the fact it doesn’t work very well make me want to replace it. I like the guy who wanted to put two units in since he talked a lot about running them low and constantly to improve humidity levels. Even when it is somewhat cool upstairs it’s still muggy.

follow up note on the insulation. Today was the first real summer like day. 85F going to 90 in a few days. We had the windows open and it’s been comfortable. 75 downstairs, 2nd floor walls at eye level were 78. Second floor ceiling 78. Top of attic insulation 95. Roof sheathing 130 behind the radiant barrier. Putting some effort into the attic definitely helps.
 
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EbS-P

Minister of Fire
Jan 19, 2019
802
SE North Carolina
I got one of these to monitor temp and humidity in my crawl space this summer. It’s a neat gadget.

Limited-time deal: Govee Hygrometer Thermometer, Wireless Thermometer, Mini Bluetooth Humidity Sensor with Notification Alert, Data Storage and Export, 262 Feet Connecting Range Amazon product
 

woodgeek

Minister of Fire
Jan 27, 2008
4,373
SE PA
Yeah, a single zone HP with a two speed compressor (and adding some brach ducts in the basement to reduce the noise and improve the balance (which is DIY-able) is the 'cheap' option, but it would work OK.

I've got a single zone HP with single speed compressor and balance is OK bc I run a strategically placed ceiling fan 24/7 in the winter. A bit of a kludge, but comfortable. When the HP dies, my next one will be variable speed compressor, to run low and slow and quiet in the shoulder seasons.

The two zones and HPs, up and down, would be VERY nice, quiet, and will be the most efficient (bc it will have more tonnage, and run at lower speed). But it will cost $10k more.
 

maple1

Minister of Fire
Sep 15, 2011
10,783
Nova Scotia
From an earlier post it sounded like the problem with the oil boiler was leaking around the DHW coils? That's minor, if so. Mine did that a couple times over the time I had it. I just replaced the coil gasket. First time i did it i installed unions to make it an easier job in the future. But not clear if that is the problem or not. Or exactly what you have for a boiler. Oil boilers usually can last a very long time. The burner could be another story.
 

begreen

Mooderator
Staff member
Nov 18, 2005
88,230
South Puget Sound, WA
The current AC is pretty loud. I threw it on today and it’s a base line 60 db on a first floor room. The booster fans for upstairs are loud and rickety when they are on. All in all it’s kind of sounds like riding a subway. I often turn it off just because the sound gives me a headache. That and the fact it doesn’t work very well make me want to replace it. I like the guy who wanted to put two units in since he talked a lot about running them low and constantly to improve humidity levels. Even when it is somewhat cool upstairs it’s still muggy.

follow up note on the insulation. Today was the first real summer like day. 85F going to 90 in a few days. We had the windows open and it’s been comfortable. 75 downstairs, 2nd floor walls at eye level were 78. Second floor ceiling 78. Top of attic insulation 95. Roof sheathing 130 behind the radiant barrier. Putting some effort into the attic definitely helps.
I grew up back east in a house with no AC. We opened up the windows in the evening to let in the cool night air and closed them in the morning. We had a whole house fan in the attic gable with a ceiling vent that helped pull in the cool night air too. This worked reasonably well except on the hottest, muggiest days.
 

NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
406
Massachusetts
It’s a Burnham and yes leaking from the dis-used tankless dhw coils and around the faceplate. Suspect since it hasn’t been leaking too long that most of the corrosion is just sediment from the water accumulating and that the fasteners are in repairable shape. You never know till you try and you don’t try unless you know what you are doing.

We once had a family friend over who is a plumber and I was showing him the crazy labyrinth that is necessary to run two different water heaters seasonally. I pointed to a valve that looked in totally good shape and he he yells “Don’t touch that!!! Since you’re not a plumber you are only allowed to touch that twice a year, once when you turn it on and once to turn it off. Even better, call me and I’ll turn it for you”. Little does he know I turn all the valves once a month to make sure they don’t get stuck... but this is boiler thing is out of my league.

EB4ADC9C-C4AE-4DEC-8FF7-D9CF6CD5CFA4.jpeg
 

NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
406
Massachusetts
I grew up back east in a house with no AC. We opened up the windows in the evening to let in the cool night air and closed them in the morning. We had a whole house fan in the attic gable with a ceiling vent that helped pull in the cool night air too. This worked reasonably well except on the hottest, muggiest days.
Yes, when it’s reasonable out at night I often open the door to the attic stairs and open the windows on the table ends of the attic. I then have a few window fans blowing in. Often it’s better to give a place for the warm air to go than to try to cool it off. The humidity can still be tough if you don’t directly feel the air movement from fans though.
 

begreen

Mooderator
Staff member
Nov 18, 2005
88,230
South Puget Sound, WA
The irony is that my dad was a mechanical contractor, but the house was boiler heated so AC would have required a whole new system installed.
 

velvetfoot

Minister of Fire
Dec 5, 2005
10,055
Sand Lake, NY
Crazy labyrinth? You ain't seen nothing. The blue tank came with the system and hasn't been used since I got the other tank. You got me thinking about draining the electric tank and maybe running it and the heat pump water heater, but I'm also lazy.

My boiler is a 2003 vintage Burnham boiler. I don't know how long those cast iron oil boilers can last.
 

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maple1

Minister of Fire
Sep 15, 2011
10,783
Nova Scotia
It’s a Burnham and yes leaking from the dis-used tankless dhw coils and around the faceplate. Suspect since it hasn’t been leaking too long that most of the corrosion is just sediment from the water accumulating and that the fasteners are in repairable shape. You never know till you try and you don’t try unless you know what you are doing.

We once had a family friend over who is a plumber and I was showing him the crazy labyrinth that is necessary to run two different water heaters seasonally. I pointed to a valve that looked in totally good shape and he he yells “Don’t touch that!!! Since you’re not a plumber you are only allowed to touch that twice a year, once when you turn it on and once to turn it off. Even better, call me and I’ll turn it for you”. Little does he know I turn all the valves once a month to make sure they don’t get stuck... but this is boiler thing is out of my league.

View attachment 278969
Oooh, ya, that does look pretty crusty.
 

EbS-P

Minister of Fire
Jan 19, 2019
802
SE North Carolina
Have you checked out the MR Cool systems. They are very intriguing. I still don’t have a good assessment of the quality versus cost and if they are a good investment but it’s product that’s out there. They claim 100% heat output down to -5F. (I think I saw that somewhere).

 

NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
406
Massachusetts
Have you checked out the MR Cool systems. They are very intriguing. I still don’t have a good assessment of the quality versus cost and if they are a good investment but it’s product that’s out there. They claim 100% heat output down to -5F. (I think I saw that somewhere).

Very interesting video of the performance of just the heat pump with no supplemental resistance keeping a house at 70F while it was -24F outside. They didn’t say how much electricity it was using at the time though. I assume it would have been down near 100% efficient if not below which would mean in a real world application you’d be better off with resistance heat I’d think. But on the other hand it would be nice to know you won’t go cold without resistance heat even if you use a little extra electricity. Either way pretty impressive and breaks some myths about heat pumps (or at least this one) in very cold weather.
 

woodgeek

Minister of Fire
Jan 27, 2008
4,373
SE PA
For the record, the coil plate of my old boiler looked more crusty than that for all the 6 years I owned it, but didn't drip when it was hot. I just let it stay hot all the time and never got it fixed.

Doesn't seem likely to be the sort of thing that will open up and cause a flood suddenly. I don't know if I would bother fixing it, and would just use the boiler for a few more years as is, esp if it doesn't drip when hot.

If it makes you nervous, two suggestions:
1. put a pan an a water alarm under it...some of them are now wifi enabled to alert your phone.
2. shut it down when not in heating season and TURN OFF the makeup water supply. Turn it back on when heating season returns. When the boiler cools without makeup water, it will relieve the pressure behind the leak, and probably stop a slow leak entirely. That way there is NO WAY the leak can open up and flood your house, e.g. while you are having a relaxing summer vacation. Worst case is just gravity drainage of a few gallons of rusty water....which will not happen anyway.

I say go for a 5 ton heat pump, have an HVAC guy add a few branches (or upsize existing branches) to your ducts to up its CFM capacity 20-30%, to rooms that you think are underserved. Flex is quieter than hard ducting. And then run the boiler AS IS 4 mos a year, assuming it doesn't start to drip when hot. After a season or two getting to know the new HP (e.g. running it with the boiler shut down sometimes to see how low it goes without strips), get a $$$ new service line and strips put in, and the rip out the old boiler. You can then decide if you want another HP in the attic (or a minisplit in the basement), or to further expand the ducts to the existing unit for better balance/quiet, etc.

And this is basically just what I did 9-11 years ago. Except you already have the HPWH.
 

begreen

Mooderator
Staff member
Nov 18, 2005
88,230
South Puget Sound, WA
The guy I met today recommended a single zone unit from Bosch.

Bosch BVA60WN1M20 Air Handler

BOVA60HDN1M20G Condensing unit

As expected he really down played the ability of heat pumps to keep up with very cold weather and was inclined to keep the oil as a backup / no electric heating coils now, though they can be added to the unit later. Also didn't get the warm and fuzzies (or cool and fuzzies in this case) on AC performance upstairs. Flow will be lower and coming out the floor registers the air will want to sink back downstairs. Hopefully he's under-promising and over delivering...

Installed cost is 16K and that doesn't do anything for my boiler situation... I assume this single zone / no coils option is going the most bare bones so the cost isn't making me too enthusiastic - especially if there's not a great performance impact during the summer upstairs where it gets hot and muggy.

Still need to get a cost from the guy who talked about a separate handler in the attic.
I would be leery of getting the Bosch. They make some good tools, but are not known for HVAC. If they abandon this market you could be left out of luck when service or parts are needed.
 

peakbagger

Minister of Fire
Jul 11, 2008
6,350
Northern NH
I am on a few industry mailing lists and every worldwide firm is jumping on the bandwagon to sign up HVAC firms to sell their product that they probably are already selling somewhere in the world. There are also a few US firms trying to get their foot in the door. Everyone assumes that the federal government and utilities will be subsidizing retrofits heavily. Its a potential gold rush and no one knows who will shake out. No doubt the Chinese will rush in with copycat low price equipment and undercut all the big name firms. The trick with all this equipment is its more complex than its predecessors and potentially need more skilled maintenance by folks with access to factory parts and service manuals. Local HVAC firms are making their bets on who they want to be in bed with in the long term.

Another aspect is the current HCFC being used in most equipment is being phased out and it doubtful its replacement will be drop in. Good chance ten years out, when the current units start to fail it will not be worth fixing them.
 

Prof

Minister of Fire
Oct 18, 2011
556
Western PA
The guy I met today recommended a single zone unit from Bosch.

Bosch BVA60WN1M20 Air Handler

BOVA60HDN1M20G Condensing unit

As expected he really down played the ability of heat pumps to keep up with very cold weather and was inclined to keep the oil as a backup / no electric heating coils now, though they can be added to the unit later. Also didn't get the warm and fuzzies (or cool and fuzzies in this case) on AC performance upstairs. Flow will be lower and coming out the floor registers the air will want to sink back downstairs. Hopefully he's under-promising and over delivering...

Installed cost is 16K and that doesn't do anything for my boiler situation... I assume this single zone / no coils option is going the most bare bones so the cost isn't making me too enthusiastic - especially if there's not a great performance impact during the summer upstairs where it gets hot and muggy.

Still need to get a cost from the guy who talked about a separate handler in the attic.
Holy cow! I had the same unit installed last summer for $6500, including new ducts in the basement. It looks like the units went up a bit in price, but no where near the cost difference. That being said, I couldn't be happier with the Bosch system. The bump to my electric bill has only been about $20-40/mo for cooling. Used it for heat in the shoulder season, and didn't notice much increase in electric bill then either.
 

Texas123

Member
Apr 12, 2016
136
Stephenville, TX
Surely there are some on line HVAC load calculators which can be used? I mean you need to know the heating and cooling loads and then add a few percentages. Down here in Texas the rule of thumb is one ton (12000) BTUS of heating or cooling for each 500 square feet.