Leaning towards heat pump
Looking at a ~1920 home in northeast with plaster and no insulation. 800 SF each floor not counting ~500 SF finished basement and same for attic. The current system consists of:
- Heat: Recessed steam radiators with a fairly new ProSelect FORCE natural gas furnace.
- Cooling: Window units.
Going to likely gut renovate, insulate, and will definitely installing a split system for AC - debating whether to do two zone (2 condenser and 2 air handler), 1.5 ton each floor, or a single unit for both.
Regarding heat, everyone will tell me steam is the best (where "best" = most comfortable), and I get that, but a builder up here told me about the Mitsubishi Hyper Heat Pump and said the comfort level and efficiency is on par, if not better, than steam radiator, and I can use the same duct work. I'm not north enough to need to worry about single digit or low double digit temps in the winter.
I'd appreciate other's thoughts as to best way to approach this.
Comments
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Define "northeast" and we may be able to give you a better answer…
There are some parts of southern and coastal New England (though not Down East) where a heat pump may be able to serve — provided it, and your ductwork is properly designed for heat, not cooling. But it will only serve. As a shoulder season heating system it will be nice anywhere in the northeast — but in the colder regions of the northeast, nope. Sorry. It will struggle if it can cope at all on the colder days, and your electric bill will make you weep.
And the problem is not solved by better insulation. The problem is that the heat output of a heat pump drops as the outdoor (source) temperature drops — so the more you ask of it the less it can give you.
Keep the steam, if only as a backup when you are feeling chilly.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Technically the more you insulate the less you're asking of the heat pump so that does help it. But you're going to say it'll still be oversized for cooling.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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heat pumps work well in the NE but you really need a back up plan for when that heat pump is down and parts are several days out.
Steam or hot water systems can operate off a small generator during blackouts also.
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Most don't have such a luxury in my experience.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Dual fuel is a fine option. Don’t just rely on gas.
In my opinion, the real question is steam boiler vs. furnace. You can keep gas AND ditch steam, furnaces are cheap and small. Going with dual fuel lets you optimize a bit - you can get a lower end furnace and a lower end heat pump.Idk what you mean by efficiency but steam is easy beat by a heat pump on efficiency (gas in to heat out). Not that close.
Check your fixed gas fees, it may make sense to totally ditch gas. Either way, a heat pump is a no-brainer if you’re installing AC regardless.0 -
I would never rely 100% on a heat pump!
I like them
They’ve come a long way
They do work
in the NE you need back up plan.1 -
Keep the steam. That Force boiler will outlast any scorched-air furnasty, and will give much better comfort. And that heat-pump pusher who wants to sell you a HyperHeat is full of……. hot air (yeah, I know what you thought I was gonna say ). There is no air-based system that can equal the comfort of steam.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting
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Seeing as you are doing a complete remodel you might consider converting from the steam system to forced hot water. Once you have insulated well you might be able to get away with the desired deep in condensing mode supply water temperature. This gives you an efficient and reliable carbon burner system. Install your HP mini splits and run them. Economy typically goes with the single condenser and dual evaporators but sizing needs, installation ease and redundancy can sometimes favor separated systems. Set the boiler to lock out until the OAT drops into the range where the heat pump starts to struggle. The boiler could trigger a relay that cuts out the heat pump automatically when bringing on the gas fired hot water system.
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And why would you tear out the steam system and convert to hot water? Yes, if you put in big enough radiation you may be able to run the hot water in the condensing range much of the time — but that is the same temperature range at which a heat pump will actually work quite well. When it gets really chilly out, the hot water system, unless the radiation is really really big, won't be condensing, and the fuel efficiency will be the same as steam. So what have gained? A big hit to the budget… and nothing else.
It's a matter of balancing priorities. If you have the budget for it, and don't mind a few weeks in the winter when you are uncomfortable and are young enough so that that is not a health consideration, and you want to go all electric, then a top end heat pump installation may be the way to go. It will be the most expensive option. Otherwise, a heat pump sized for the shoulder seasons and cooling has some advantages — provided you need the cooling, or there are some areas where you need spot neat. That would be combined with keeping the steam system to do the heavy lifting in the colder months. If you don't really need the cooling, then just keep the steam.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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Go to this page and look up the heating design temperature for your county:
https://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/County%20Level%20Design%20Temperature%20Reference%20Guide%20-%202015-06-24.pdf
Read this article:
For how to estimate your heating load based on historical fuel usage.
Go to
https://ashp.neep.org/#!/
Look at some heat pumps, and click on "Advanced Data - System Sizing." Put in your zip code and your calculated heating load and click on "run system sizing."
My personal opinion is that the Mitsubishi M-Series represents the state of the art right now, I'd start by looking there:
https://ashp.neep.org/#!/product/34583/7/25000/95/7500/0///0
The data that NEEP will provide will give you a very good idea of how a heat pump will work in your house in your climate.
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I think the easy option is install a heat pump now then in 4 months see if the steam is actually a must have. Then you can decide if you want to keep it. Your decision, not some installer’s and certainly not us randoms.
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@Jamie Hall A lot of assumptions on my part: Steam radiation is traditionally over sized. Remodeling the structure for efficiency would dramatically reduce loads. The existing boiler is dysfunctional or very old. A fully condensing ODR system would offer a considerable efficiency gain over steam. I can hear grandpa asking "you know what assuming does right?"
I did say "might consider". I read "furnace" and though it was additional forced air. I didn't realize it's a newer gas boiler.
I knew some would disagree for the love of steam. That's fair. If the back up system is very rarely needed then of course any efficiency gains of a conversion would take a long time to break even.
I prefer forced hot water over steam but agree converting a functional steam system, even if it's way oversized, is bad practice. You already know It's easier to find people to fix forced hot water. I would argue a hot water system is more constantly comfortable considering the less than ideal variables of different installations. I'm sure a good steam system that's properly sized and balanced is very comfortable. FHW is easily adaptable for zoning. Design depends on constraints, goals and budget.
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Are the radiators capable of hot water heating?
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Well said.
I truly appreciated the preference for FHW vs Steam. I'd maintain a steam system forever if I lived inside the dwelling. If I leave the steam system by itself, the chances of it surviving without an issue are just about nil.
Steam systems need a daddy. HW systems do NOT!
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I disagree
Steam is about as simple as you can get
Generate Steam
no pumps
No fans
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…………..skim needed
…………..blowdown needed
…………..water needed
…………..vent maintenance needed
…………..balancing issues addressed
Steam is NOT as simple as you can get!!
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I also disagree, @LRCCBJ . If a steam system is not seriously abused (the most usual culprit is over pressure) it can and often will last a century with no attention at all to the system — though it is likely that a replacement boiler or two may be needed in that time (Cedric is the third boiler powering his system; the first was a big H,B Smith —- which was still working fine after 40 years, but a bit low on efficiency. The second was part of a misguided attempt (not by me) to save money by heating only part of the structure; long story) — but that is also true of hot water.
Steam systems, though, often suffer from misguided "upgrades" or other tinkering. If there ever was a mechanical system which required the maxim "if it ain't broke, don't fix it" it's steam heat.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Simple as long as….all the things.
Both types of systems need to be set up well and regularly maintained. Air locked loops, clogged steam vent, failed pumps, trapped condensate noise, failed expansion tanks, carryover . Tit for tat steam vs HW isn't very valuable. I see experienced well respected plumbers who don't understand the basic principles of hydronics mess up forced hot water regularly. There are many hydronics people who can get a boiler to make steam and then screw up the distribution or maintenance due to poor understanding. The benefits of steam are many and a working system should be respected but there are reasons steam is rarely a new build choice.
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Heat pumps
Lack of skilled techs
Several thermistors, transducers, inverters that can and do go bad or are miss diagnosed.
refrigerant leaks.
power failuresOn
And
On
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Ductwork is being installed for AC. I think the top 3 options (in no order) are:
- No gas backup
- Gas steam backup
- Gas furnace backup.
2. Can be tried before either 1 or 3. If 2 isn’t needed or desired, then we can try 1. If that’s not sufficient, then 3.
Free, free, then cheap makes the most sense to me here. I wouldn’t install a 3rd heating method (forced hot water) for a backup system.
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I'm with you on this, @Hot_water_fan
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
A serious lack of skilled techs seems to be universal. That said, in my area, I'm guessing I could find more than ten people capable of diagnosing and repairing anything on a big name mini split for every one person who has a the slightest grasp of steam. Turns out steam doesn't cool and lacks other desirable attributes so there's a good reason to incur the complications of refrigerant. A bit of a straw-man there. Now it's HP's vs steam? Sorry to the OP.
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@Hot_water_fan I suggested looking at forced hot water thinking the steam boiler was shot and the structure was being stripped to the bones. I wasn't suggesting a 3rd system, I was thinking of utilizing the existing radiators and piping converting to a two pipe hot water system.
The existing newer "boiler" and installing new a/c ducting makes that approach a poor idea.
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My system has been running since 2011.
I've had zero vent maintenance.
Skimming took place the first year only.
Blow downs?
Balancing is required with every system out there in one form or another.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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@Toasted Proper duct system sizing is critical in order to take full advantage of HP heating. Installers tend to overestimate the air handlers air movement capabilities and that limits heating capacity at the lowest outdoor temperatures. I've seen this a few times, the installer is questioned about duct design, they insist it's done correctly but when the paint drys there's little that can be done when it only move 60% of designed air volume. As suggested above, finding a local pro to look at your case is worth it.
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Thanks everyone. Doesn't get that cold over here - Philly area. To my understanding, a Mitsubishi Hyper HP should be fine.
And as noted, I am already doing the duct work for the cooling.
I continue to hear that having a backup makes sense, but it seems the HP would be sufficient. That said, if I removed the radiators, could I convert the steam to hot water with an exchanger and then use that for a forced air approach despite it being essentially the worst type of heat?
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If you’re doing forced air, don’t use a boiler. So many more extra parts and expense for zero benefit.
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Ah. Philadelphia area? You don't need a backup to a cold climate heat pump, provided two things happen. First, the units chosen are designed for cold climate, and are sized for the heating load, not the cooling load. Second, that the ducting is designed an installed to be sized, and supplies and returns located, for heating, not cooling.
If you manage those two things you should be comfortable enough, and you can not worry about a backup.
In response to your last question, no. That would get you the worst of all worlds.
And I have to apologize somewhat — I had the impression that you were in the northeast somewhere, which Philadelphia is not.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
The only heating system I haven't lived with is steam.
Of all the systems, hydronic and FA, without question radiant is the best. In addition to quiet and comfortable, it has one feature no others do, invisiability! In a small floorspace home, that can a huge plus. This would include radiant ceilings and walls.
A close second would be thin individually controlled panel radiators.
My worse experience was FA heat pump, geo system. In cold conditions it would puke out a low temperature, uncomfortable breeze. It would maintain room temperature but nowhere near the comfort of warm floors and surfaces surrounding you.
I guess everyone balances their definition of comfort, along with budget, and the ability of converting the system.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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Would you rather live with a very poorly designed and installed radiant system. (Huge imbalances and terrible overshoot/lag in rooms with large windows)
Or a very well designed and installed forced air system?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Not a fair comparison, @ChrisJ . You can do better than that. The proper one might be which would you rather have, a properly designed and installed radiant system, or a properly designed and installed forced air system?
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
But the comparison everyone always seems to make is a poorly designed and installed heat pump against a well-installed radiant system.
I will acknowledge that sizing is more demanding with heat pumps, the incentive is to undersize them and there's not much you can do after the fact to correct for that.
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odd question? Apples and oranges
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
That's actually the point I was trying to make.
I guess I did a bad job at it. It happens.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Even then, you should be comparing a well installed forced air heat pump system to a well installed hydronic system AND a well installed AC system. Americans want cooling!
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Radiant cooling is nice too.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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As long as everyone is on board with this, that would be great to see. I tend to see a lot of FUD regarding heat pumps.
NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el0 -
I should live so long…………….
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting0 -
We were discussing a FHW system…………..NOT heat pumps.
Lack of skilled tech is far more pronounced with a steam system! That is the primary reason people abandon them!
Thermistors……….transducers……….inverters………….on a simply FHW system? Get real. They don't exist!
Refrigerant leaks on a FHW system…………apparently you need to study this a bit more!
Power failures………….the steam system won't operate either without intervention!
And on and OFF…………..you have no good argument.
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If a steam system is not seriously abused (the most usual culprit is over pressure) it can and often will last a century with no attention at all to the system
This is seriously incorrect. This site offers hundreds of examples of low water, clogged returns, clogged pigtails, failed pressuretrols, failed vents, contaminated water that needs attention…………the list is endless.
Your bias toward steam only works if YOU are in attendance and maintain the system. I believe that's your sole responsibility…………correct?
I have plenty of examples of FHW systems that have gone for years with no attention. I have one steam system that was designed and installed PERFECTLY and it is a virtual primadonna. Others will have similar experiences.
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