Old house, old steam boiler & radiators, possible to electrify?

johnnyoops

Hi-

Homeowner here with an early 19th century farmhouse in coastal New England. It's fairly large for such an old home - about 4500 sqft, and has old windows with storms and so-so insulation. It has an enormous 1930's or 40's oil-fired boiler that (fingers x'ed) just keeps on ticking along. I'd love to electrify the house, or at least increase the efficiency substantially, but I'm a big fan of trying to get to entirely renewable or as close as possible - and I'm willing to incur some long-payback cost to do so. I'd also love to stay on hydronic heat / existing radiators if possible - both because it's consistent with the look of the home, and because I love radiant heat (and I couldn't really get underfloor into a house of this age without massive work).

So as I understand it, my options are:

1. Replace steam with hot water, and convert to geothermal or air-to-water heat pump. Cost of conversion likely very high because (a) no contractor wants to deal with the crud in old radiators and lines, and (b) the amount of repiping is likely high due to large main-lines with attendant heat loss and leaks because hot water runs at higher temps.
   
2. Go entirely mini-split or central forced air off of ASHP or geothermal. I really really would love to avoid forced air, the sound of moving air drives me bananas.
   
3. Wait for the laws of physics to change and/or a residential steam-generating heat-pump to arrive. There's news from Europe of high temperature residential heat pumps coming, but they're definitely hot water not steam.
   

Does anyone have any advice on what to do in this sort of situation? Does anyone know any really good New England HVAC 2.0 type specialists? Anyone have any experience with this kind of project? Is my best bet to keep my old boiler ticking along as long as I possibly can in the hopes that electrification for this type of application gets better in the next few years? Or install a new high efficiency propane boiler? Or bite the bullet and accept that forced air / minisplits are the only way to go?

Thanks,
John

Jamie Hall

One comment first -- steam is a good deal hotter than hot water. This goes with your option 1, and there are several main aspects to option 1. The first is that since steam is a good deal hotter than hot water, the radiators -- even if they are adaptable to hot water -- will only put out about two thirds the heat on hot water than they do on steam -- even if the hot water is truly hot (180), which is beyond the reach of heat pumps and also means that a hot water boiler would be no more efficient that a steam boiler.

Your comment on leaks under No. 1 is quite correct. Hot water runs at 15 times the pressure of steam, and thus steam systems converted to hot water usually leak.

Also, depending on your steam system, it may not even be possible to use the existing radiators -- even if they don't leak -- and it won't be possible to use most of the existing piping.

All of which is to say, in a roundabout way, that converting from steam to hot water rarely works well, if at all. Trying to couple that with going to the low temperature water produced by a heat pump, I'd honestly have to say that it is highly unlikely to work, and I certainly wouldn't contemplate trying.

I couldn't agree more with your number 2, and you didn't even mention the hassle of adding pretty extensive duct work.

On Number 3. The laws of physics aren't going to change. Although there is no theoretical reason why a steam generating heat pump can't be made, I've seen no activity on that.

So... bottom line is that I would strongly recommend keeping the steam. If the boiler is giving trouble -- particularly if it is leaking -- replace it with a correctly sized new steam boiler. Otherwise while, if it is very old (over 30 years) you may gain some efficiency, it won't be enough to cover the cost. A much better use of the money will be to tighten the house up as much as you can without risking damage. If it really is old windows and they haven't been updated, a good carpenter can make them as draught free as anything modern would be, and that coupled with good storm windows will do just as well -- at a lot less cost -- as anything but very top end modern windows. Pay attention to the sills and the area around the foundation; it's very common for there to be significant air leaks at that point, and there are a variety of foam products which can do a good job of stopping them up. Insulation is a mixed bag. It may be possible to blow insulation into the walls without risking damage to them, but if it is original plaster that may not be advisable. Adding insulation to the attic, however, is almost always possible and, provided you keep some air circulation, quite advantageous.

ayetchvacker

This product is a water-water heat pump capable of 160° supply temps via a cascade system. https://www.nordicghp.com/product/nordic-products/high-temp-water-to-water/

You would need a first rate contractor to do this type of work. If the building envelope gets significantly tighter and more insulated you may be able to heat using the current radiators at a lower supply temperature. But make sure your contractor does the math or it might not be sufficient. 

bobbob

Some business I saw recently restores old radiators, and converts them to electric with elements similar to what electric hot water heaters use. I believe they bolt into the places where your current steam valves go. I didn't pay alot of attention and am not sure but surmise that the rads have to have water in them. It would seem extremely expensive for electricity. BTW, my little brother hates it when people use the term "hot water heater." If the water was hot you wouldn't have to heat it. He has a point, but everybody calls them that...

Hot_water_fan

You’ve got it. You could use lower temperatures, it might require replacing some radiators. You can get up to 160 with heat pumps, which puts you in the ballpark of steam if the original radiators were oversized (likely) and if you can bring down heat loss a tad. Or just keep a different backup source for the highest water temperature days.

Do you want AC? If so, cost of electrification on the heat side is negligible. 

johnnyoops

Hot_water_fan said:

You’ve got it. You could use lower temperatures, it might require replacing some radiators. You can get up to 160 with heat pumps, which puts you in the ballpark of steam if the original radiators were oversized (likely) and if you can bring down heat loss a tad. Or just keep a different backup source for the highest water temperature days.

Do you want AC? If so, cost of electrification on the heat side is negligible. 

But don’t I have to re-pipe everything if I were to convert to hot water?  I’ve read that it won’t work if I keep the radiator in series (as I’m pretty confident they are). I’m not sure what the cost would be to put that much Pex in, fishing through old walls etc. Also, with the old huge main steam line (looks like 4” around) I’ve been told that the heat loss from even 160 degree water before it reaches the radiators would be insane. 

Or is that not necessary?  How do I find a New England contractor who knows how to evaluate this kind of work?

Thanks.

Steamhead

Jamie Hall said:

So... bottom line is that I would strongly recommend keeping the steam. If the boiler is giving trouble -- particularly if it is leaking -- replace it with a correctly sized new steam boiler. Otherwise while, if it is very old (over 30 years) you may gain some efficiency, it won't be enough to cover the cost. A much better use of the money will be to tighten the house up as much as you can without risking damage. If it really is old windows and they haven't been updated, a good carpenter can make them as draught free as anything modern would be, and that coupled with good storm windows will do just as well -- at a lot less cost -- as anything but very top end modern windows. Pay attention to the sills and the area around the foundation; it's very common for there to be significant air leaks at that point, and there are a variety of foam products which can do a good job of stopping them up. Insulation is a mixed bag. It may be possible to blow insulation into the walls without risking damage to them, but if it is original plaster that may not be advisable. Adding insulation to the attic, however, is almost always possible and, provided you keep some air circulation, quite advantageous.

THIS!

Your house will never be comfortable in the winter with a heat pump, or any sort of forced-air "heat".

Post some pics of the boiler and some radiators. Depending on when they were installed, you might have some real beauties. Don't waste them.

johnnyoops

Nordic has one dealer north of Boston (probably 90 minutes away).  I reached out to them. 

But do you have any suggestions about how to find a first rate contractor in my area (Rhode Island)?

ayetchvacker said:

This product is a water-water heat pump capable of 160° supply temps via a cascade system. https://www.nordicghp.com/product/nordic-products/high-temp-water-to-water/

You would need a first rate contractor to do this type of work. If the building envelope gets significantly tighter and more insulated you may be able to heat using the current radiators at a lower supply temperature. But make sure your contractor does the math or it might not be sufficient. 

Hot_water_fan

I’ve read that it won’t work if I keep the radiator in series (as I’m pretty confident they are).

Why do you think they’re in series? 

Jamie Hall

johnnyoops said:

Hot_water_fan said:

You’ve got it. You could use lower temperatures, it might require replacing some radiators. You can get up to 160 with heat pumps, which puts you in the ballpark of steam if the original radiators were oversized (likely) and if you can bring down heat loss a tad. Or just keep a different backup source for the highest water temperature days.

Do you want AC? If so, cost of electrification on the heat side is negligible. 

But don’t I have to re-pipe everything if I were to convert to hot water?  I’ve read that it won’t work if I keep the radiator in series (as I’m pretty confident they are). I’m not sure what the cost would be to put that much Pex in, fishing through old walls etc. Also, with the old huge main steam line (looks like 4” around) I’ve been told that the heat loss from even 160 degree water before it reaches the radiators would be insane. 

Or is that not necessary?  How do I find a New England contractor who knows how to evaluate this kind of work?

Thanks.

Yes, you will have to repipe everything. Steam radiators are never in series. If it is one pipe steam, you will have at the very least to run a complete new set of return lines. If it is two pipe steam, you might be able to get away with reusing some of the riser piping but, to achieve balance they will have to be individually fed and returned, and you need all new piping in the basement. Also, on two pipe, the steam radiator valves and traps will need to be changed out for hot water; on one pipe, of course, you would need change out the valve and add a new fitting for the return. And, of course, pressure test everything -- as I said, water runs at ten times the pressure of steam.

The basement main should be insulated. If it isn't, do. As soon as possible. The heat loss on steam isn't that great, though it is significant, but no insulation makes heat slower and much harder to balance.

I'm intrigued by the "in the ball park" comment. At 160, the radiators would have very roughly half the heat output they do now on steam. There is a common misconception that steam radiators were oversized -- which is a very dangerous assumption to make. Sometimes they were. Often they were not.

I have no recommendation for a New England area contractor who would be both responsible and willing to do the work.

Hot_water_fan

Ha @Jamie Hall I included several caveats! Maybe I should have made them all inclusive and said 1. Check heat loss vs EDR, 2. Bring down heat loss and 3. Use a backup. Plus I mentioned adding radiation.

You can get up to 160 with heat pumps, which puts you in the ballpark of steam if the original radiators were oversized (likely) and if you can bring down heat loss a tad. Or just keep a different backup source for the highest water temperature days.

johnnyoops

This is the boiler, in case anyone is interested. Guessing it was once coal fired. The brass storage tank is crazy. There’s no way I can even imagine how they even got the boiler in the basement - no way it was fitting through a bulkhead. 

Jamie Hall

That's a beauty -- but it is a system which could indeed gain sufficiently in efficiency to make considering a new boiler and domestic hot water system worth doing. And for that I can recommend someone: @New England SteamWorks (just click on the name to send them a personal message).

And get those steam lines insulated...

Steamhead

That boiler was installed in the late 1950s or early 1960s. It is a "wet-base" type in that the cast-iron, with water on the other side, extends below the firebox. This provides some more heat-transfer surface.

The Carlin burner is newer. I can't see the model number, but I'm certain it is a flame-retention type, which is the most efficient type of burner out there.

ChrisJ

Sigh.

I guess besides the constant selling of "efficiency" we now have "electrify" as the new buzz word.

That didn't take long.

@johnnyoops I'd ignore fads and work on getting the house sealed up and insulated. That'll make more sense in the long run and make the structure more comfortable.

I'd also make sure the current system is reliable and working correctly and safely.

There's plenty on this forum to help steer you in the right direction as far as those things.

WMno57

johnnyoops said:

Is my best bet to keep my old boiler ticking along as long as I possibly can

Yes.

johnnyoops said:

in the hopes that electrification for this type of application gets better in the next few years?

Realistically, electric heating technology that could be economically installed in your home is 20 years out, if ever.
You can heat a house on your lot in your climate with heat pumps. The project starts with large yellow machines that run on fossil fuel and sending everything to a landfill. Then build a clean sheet of paper 800 square foot super-insulated home with ductwork for a heat pump.
You have a very nice steam boiler that is much newer than you think. It even has a drop header. Use the Find a Contractor tool on this site and hire someone with a combustion analyzer to tune your Carlin burner. You can get your current setup to efficiencies in the low 80s. A propane mod-con would never get to it's advertised efficiency in your home. Also, the payback period because of the labor costs associated with the radiators would be NEVER.
Be warned: There are contractors who will take advantage of your lack of knowledge and desire to be green. They will be glad to rip out that nice boiler and hack in a so called green high efficiency system.
It wont be as green as they claim. It wont save you money. The only green in that situation is the green you pay, and they pocket.
If you want to be green in that house, insulate and reduce air infiltration. If you want to be greener, or get off fossil fuels, start over with another house.

WMno57

An easy project would be to insulate the steam supply lines. You don't need to insulate the returns.

delcrossv

"Be warned: There are contractors who will take advantage of your lack of knowledge and desire to be green. They will be glad to rip out that nice boiler and hack in a so called green high efficiency system.
It wont be as green as they claim. It wont save you money. The only green in that situation is the green you pay, and they pocket."

Bingo. There's more to saving the environment than just getting new stuff. Tune the burner, insulate your mains and that pretty storage tank, look for air infiltration and fix it. Done.

EBEBRATT-Ed

@johnnyoops

Do what @ChrisJ , @Jamie Hall & @Steamhead said

Tighten the envelope, windows insulation and caulking this will help no matter how you heat. And get in touch with @New England SteamWorks to look at your system this summer.

Robert_25

I have a heat pump that we installed in our 110 year old house mainly for AC. I have been pleased with how economical it is to heat the house in the fall and spring, but there is no way I would want to depend on it in cold weather. Lucky for you there is already a great heating system in your house that performs at its best when it is bitter cold. Have a steam pro give the system a good once-over and insulate the piping.

Are you still using the oil boiler to produce domestic hot water? It looks like that brass storage tank is connected to a tankless coil. A heat pump water heater may be a good way to knock down your oil consumption and help dehumidify your basement in the summer.

ronaldsauve

Start with upgrading the envelope. You can have the most efficient means of heating in the world, but it will just be “an efficient means of pouring water into a bucket with a big hole in it”. You will be “pouring” lots of money into the efficient means of heating if you don’t first address the envelope. Pay a lot of attention to air sealing as well as insulation, and don’t overlook any areas. You can airseal and insulate 99% of your envelope, but then all of your heating, or cooling, will then go to the 1% that you overlooked, along with all the moisture in that heated air, resulting in condensation, mold, and rot. But if you pay attention to your envelope, upgrading that, you’ll only pay for it once, it won’t need any maintenance, and then you won’t have to use much of your limited budget on other efficient means of providing energy, because you will have fixed the “hole in your bucket”.

OuterCapeOilguy

Someone did their best by way of keeping the old boiler operating; I see it's retrofitted with what appears to be a Carlin 100CRD, excellent choice for a retrofit on an old, low-static-pressure boiler. Get rid of the oil return line and crappy cartridge-type fuel filter and install a deaerator with a spin-on 10-micron filter. Better yet, replace the boiler with an up-to-date steam boiler like a Weil-McLain SGO-series, properly sized and fitted with a Carlin EZ1-HPW burner with a Pro-Max primary. No reason to get rid of the oil, in my opinion, unless you are after freeing up space taken up by the fuel tankage. The brass tank hot water tank, while picturesque, can be replaced with an all-stainless indirect water heater, such as a Crown Boiler Mega-Stor, with the coil piped below the boiler's water line. Trying to convert the radiators to hot water would, as Mr. Hall pointed out, be an expensive and frustrating project and likely a failure.

Flapjack3

Older homes with balloon framing have many opportunities for efficiency improvements. You can use the Building Performance Institute (bpi.org) Find a BPI Contractor to find energy auditors and weatherization contractors. 'Tightening' and insulating your home will change heating/cooling requirements for the better.

jimcloh

I think I'm one of those pointy-headed folks you guys like to laugh at. I thought residential steam heat should be like:

https://www.facilitiesnet.com/hvac/contributed/Vacuum-Steam-Heating-Time-for-a-Comeback--38418

An evacuated solar tube needs no steam traps or air vents. Topologically an evacuated solar tube is identical to a boiler piped to radiators. No air in the system, no oxygen corrosion and rapid heat transport. Oh! And if you don't run your system above about 200 degrees, you can patch pinholes in a radiator with bubble gum on the outside, and paint leaky threads with latex paint. (Perhaps better patching materials could be used.)

The triple point for water is 32 degrees, so steam while usually hotter than hot water in residential systems, doesn't have to be. If your radiators aren't oversized, you can add more heaters to get the BTUs you need, be it radiators, fin tube, convectors .... You could go hybrid and run pex under the floors from an indirect hot water tank. But you have got excellent advice to reduce your heat load by tightening your housing envelope. This site has some excellent suggestions.

https://www.builditsolar.com/References/Half/DirtCheap.htm

Jamie Hall

Igor is a great engineer and has some fascinating ideas. Some of them work reasonably well. He's somewhat misrepresented on a couple of points in the first article, but there are some good points, too.

For some systems and applications.

It might be pointed out that an orificed vapour steam ssytem is a lot simpler...

The second article looks like something from the '70s energy crunch -- there's another thread on that -- with the added twist of a personal computer thrown in.