Replacement for single pipe steam heat in a converted 2 family house

SteamingatMohawk

I've had this house for 34 years. It was a typical two family near Albany, NY that was converted to 4 units, front and back, up and down. The traditional single thermostat setup has been used since the boiler was replaced more than 20 years ago. At the time of the replacement there were 3 Honeywell thermostats wired in parallel. The guys who replaced the boiler said I should only use one thermostat, so one was chosen.

Since then I spent a lot of time on improving the system with tons of help from HH contributors. A few years ago, I invested in a Honeywell wireless battery powered thermostat interacting with an Equipment Interface Module (EIM) which gave me a lot of flexibility in where to locate the thermostat. I added the gateway so I can monitor and manage the system from an app on my cell phone. This required having a hard wired connection to a router, which one of the tenants graciously allowed.

Having this setup made control of the heating system immensely more convenient, like not having to leave the basement and go through 4 doors to change the thermostat setting. At times I even had a setup with one of the original thermostats mounted in the basement and available through a switch to the boiler controls, but that feature was no longer needed with the app on the phone.

This heating season has been a problem with the fall temperatures so variable and not settling down to the typical cold day temperature levels and swings. Perhaps, it is a sign of climate change/global warming, but I am not going to debate that issue.

I've casually looked over the years at alternatives to my system and haven't come up with one that will actually work. A personal friend who works in the HVAC business has said to keep what I have until it must have work done.

Here's today's question:

For my situation, what are the options and the most common and successful replacement for my geographic area?

pgf

I'm not a professional, but have thought quite a bit about how we might convert my single pipe steam system to something else. I think the answer, these days, is clearly to install an electric heat pump system. Albany gets cold, so you probably want to leave the current system in place as a backup. Obviously tuning your existing system to work the way you want it to would be more cost-effective, but there are advantages to switching -- air conditioning and individual thermostats being the biggest immediate ones. Longer term, heating costs might be lower, as well.

paul

SteamingatMohawk

As I mentioned in other discussions, the house we built in 1987 to live in has a heat pump with gas backup and I am completely satisfied with it. The only thing is equipment in those days was limited to about 40F for heat pump lowest outdoor temperature. At that time zoning wasn't done, but it hasn't been an issue. One of my son's has a colleague who does zoning, so I could have it done, if I wanted it.

I have talked with the guys at the orange store selling mini splits and gotten these answers when I asked them what you do when the temperature goes below the minimum for the mini split.

One said what you said and to some extent my reaction was if I keep the existing system operable, why bother with adding new stuff.

The other answer was to tell the tenants to wait until the weather warms up..That's a non-starter for rentals.

I thought about converting to hot water keeping the steam radiators, but the lower operating temperature of the water 180 vs.212 significantly reduces the heat transfer rate and anecdotally can cause less even distribution of the heat. I'm not sure how much hot water baseboard would be needed in place of the radiators.

If ducts could be small enough hot air is a possibility given that the supplies to the second floor rooms already are visible in the rooms below, so it might not be such a big deal replacing the riser with a duct (maybe inside a chase for appearance sake).

The biggest rooms are the living rooms at around 200 sqft.

SteamingatMohawk

The other idea is to go with geothermal ground source with vertical not horizontal runs.

ethicalpaul

SteamingatMohawk said:

The other idea is to go with geothermal ground source with vertical not horizontal runs.

That definitely works if you have the upfront $$ (I have done it). It seems like there are still 30% tax credits available on the installation cost of them.

But do you have air ducts? Water to water isn't really a thing here in the US, and if you want cooling you basically need the ducts anyway.

I didn't mind them with my ground source system, but that was before I had experienced steam. Now it might bother me more.

SteamingatMohawk

No, I don't have air ducts, but since the rooms to be served are pretty small in this around 100 year old house, I thought maybe I could "get away with" 4 inch ducts. The living rooms in the back apartments used to be the kitchens and they are no bigger than 11 x 11ft2. Bedrooms are less than 100ft2.

The main trunk would mimic the front and rear mains from the boiler suspended at the bottom of the first floor joists. Risers would replace the steam risers location wise. As it is they run between joists out of the way of the cross braces.

It would be really cool if I could use battery powered wireless thermostats for each room connected to a main control panel .

My son's buddy does Arzel (I think thats how it is spelled) and he has one of those systems in his split level house. Because of the layout of the rooms, each of the 9 outlets would be individually controlled. I don't know if multiple dampers could be controlled by a single thermostat. If so, the bedroom and living room could be combined saving some $$.

Steamhead

@SteamingatMohawk , your steam system should work well no matter how mild the weather is. We have found that with proper main venting (and riser venting if needed) and the boiler in good tune and properly controlled, steam will distribute quickly and evenly without over- or under-heating.

What problems are you having with it?

If you wanted to do A/C, mini-splits should work well, but I wouldn't rely on them for heat that far north.

SteamingatMohawk

It's really odd. For the last several years the system has run with no complaints from
the tenants. As you may have seen on HH I have done several things over the time of my ownership to improve performance of the system and to make it easier to control the heat by installing the wireless thermostat with a wifi gateway. The only issue was if the tenant in the tstat apartment did a lot of cooking, she kept her apartment warm (apartments are small) preventing the tstat from coming on and heat the rest of the house. We solved that by having the tenant locate the tstat further from the kitchen. We even laughed about a comment by another tenant that they would put the thermostat in the bathroom while cooking.

The tenant in the tstat apartment got married; I hugged her, gave her a wedding gift and sent her on her way.

I got a replacement tenant and things immediately went downhill. He decided to make the living room his bedroom. I stated I had no objection as long as he follows the rules. He ran a fever and was advised by his doctor to open windows to get fresh air in October. The living room has one large window with smaller ones next to the large one. He also had a fan blowing air out of the apartment. The radiator is under the large window. Bottom line the heat would turn on, but the tstat would not be satisfied while he was trying to heat the world. When I discovered it, I sternly instructed him to not have windows open for extended times. Additionally, he had positioned his bed with the head less than a foot from the radiator potentially affecting the heat distribution in the room. I had him reposition the bed.

All this was happening in October with typical swings in the outdoor temperatures. At one point the tstat thermometer read 74 with the heat setting at 69. It made no sense, so I started troubleshooting. First I checked the main vents and found the one for the rear main appeared to be clogged. I replaced that vent. I decided to replace the front main vent as well, just to be sure.

I have records of the radiator vent settings and no one had changed any of them on all 9 radiators in the house.

With the temperate weather, for some reason the heat/house was no longer behaving as it had for the last few years. At times it would overheat one or more of the apartments, at other times apartments would be below 68, as low as 63-65.

I thought the problem could be the run times for the heat to satisfy the tstat and how long it would take on the warmer days for the system to cool down before it would again turn on. I have no positive proof of the current tenant manually changing the tstat settings.

So, where am I today? Because we are having an extended period of shoulder season weather, I monitor the temperature readout of the tstat and its setting as well as a separate indoor/outdoor thermometer in the tstat apartment. I positioned the outdoor sensor in the living room and have the readout in the basement. I have a camera that is aimed at the readout and can be accessed by my cell phone.
I also purchased individual thermometers with a +/-0.5F accuracy and have them in the apartments. I also bought a second laser infrared thermometer which reads about 4 degrees less than the one I had been using. The new one is more consistent with the individual thermometers, so comparison among the apartments is more consistent.

For now, I look at both devices and based on those readings and predicted weather, I manually control the heat. It seems to be working. The current dilemma is that the living room below the living room with the tstat is cooling down more than the one above with the thermostat. Increasing the venting rate of the first floor living room radiator will overheat that living room above 75.

The mystery is why with nothing done to the heating system is this happening? It seems the swing period is longer, making it more difficult to stabilize the system. There has never been a lack of steam from the boiler or at the radiators; just an imbalance of how much goes where. The only physical change in the apartment is the difference in furniture in the tstat living room and the fact that the previous tenant had curtains on the living room windows. The current tenant has not installed any curtains to date. There is nothing blocking the radiators.

As I mentioned in other HH conversations, a few years ago I did the Gill/Pajek calculations without including the radiators. I bought Dan's EDR book and am trying to match the radiators so I can include them in the calculations. When I looked at my previous data I realized I had set the Heat Timer radiator vent in the tstat room to fully open, which has a large venting capacity. Along the way, I reread the added article in the Gill/Pajek report about over venting and think that may be a factor. Trying to understand why I used such a large venting capacity, I concluded that at the time I probably thought venting that radiator quickly would be a good idea and had not yet referred to the over venting article. Today, I'm not so sure. But what doesn't make sense is that for the last 4 years there hasn't been a complaint.

Having not found any conclusive cause for the imbalance I decided to investigate the tstat. I called Resideo and was advised there is an adjustment that somehow tries to mimic the heat anticipator. The name of the setup function makes no sense to me and I didn’t even know it existed. It is function 32 named, “Temp. display offset (indoor)”. From the factory it is set at 0; the Resideo rep said to set it at -3 (the lowest setting). I did that assuming it would be like setting CPH to a higher number potentially shortening each heating cycle and having them more often. It seemed to be working in the coldest days of this fall.
I have no evidence the tstat is malfunctioning, but I bought a replacement unit as a backup if the tstat fails and because they are not available locally (Supply House is a great resource). I also bought the “Wireless Portable Comfort Control”, but have not yet given it to one of the tenants.

Matching the radiators with ones in Dan’s book has been a challenge, but I received some HH feedback about the ones most similar to what I have. An interesting factor is the EDR conversion to volume information has two numbers for my vintage radiators. The Gill report mentions Cast-iron column (circa 1900) .025 and Cast-iron tube (circa 1930) .013. My house was built in the 1920s. The difference is a factor nearly twice as the later radiators. I used .025 in the calculations yesterday and got 3 minute (Gill’s time number in the report) venting rates way higher than what is installed. I haven’t yet figured how to interpret the result, other than, some conclusion that if it takes 4 minutes instead of 3 that it isn’t a big deal, except for the large difference with the Heat Timer in the tstat room.

Believing the numbers would have me at least double the venting rate of the non-tstat radiators and reducing the tstat. Again, this doesn’t explain why the previous years were OK.

This escapade has taken a lot of time, but I learned during my working days in the nuclear navy program to only change one thing at a time when troubleshooting. If you change more than one and solve the problem, you may not learn the true cause.

As things stand today, I’m patiently waiting for the cold weather to settle in (ha ha) and hoping that will reduce the imbalance and hoping HHers can help solve this puzzle.

jesmed1

SteamingatMohawk said:

I thought about converting to hot water keeping the steam radiators, but the lower operating temperature of the water 180 vs.212 significantly reduces the heat transfer rate and anecdotally can cause less even distribution of the heat. I'm not sure how much hot water baseboard would be needed in place of the radiators.

It seems you should be able to get the steam system balanced somehow. But re your steam-vs-water question, I'm not sure your concern about "less even distribution of heat" is accurate.

I maintain our 4-unit, 4800 sw ft 100-year-old condo building in the Boston area. 4 units, 2 up, 2 down, with the house split down the middle. Two boilers, one for each side. Old cast iron radiators, about 1000 sq ft EDR. So the house is massively over-radiated, as yours probably is too.

Because of the over-radiation, we can heat the house with supply water temperatures that almost never exceed 130 degrees. The boilers start cold, run 45 minutes per cycle, and only at the very end does the supply water temp reach 130-140. Radiator surface temperatures stay around 120 or less.

Because the water temperature stays low, the heat is very gradual and even, and despite having only one thermostat per boiler (the Tstats are in the first-floor units), we have good temperature control. The Tstats are set to swings of 0.5 and 0.75, differently due to slight variations in the building envelope, but all units maintain 68-70 without large excursions. I have had to do some balancing by partially closing some rad valves in downstairs units, but the tuning is minor. Our main problem has been air in the rads, so I recently installed an Airtrol tank fitting in our plain steel expansion tank and am hoping that solves the problem.

But on your point of "even heating," during a typical 45-minute cycle, our radiators radiate only about 10% of the BTU's output by the boilers. The rest of the heat is still stored in the water and the cast iron rads. Most of it is in the water, about 60%. Another 22% is in the cast iron rads. And that residual heat slowly releases for an hour or more after the Tstat satisfies, continuing to heat the building with low temperature water.

You can see my analysis of where all our boiler BTU's go during a typical heating cycle here:
https://forum.heatinghelp.com/discussion/193741/understanding-heat-flows-in-high-mass-heating-systems-in-old-houses#latest

My conclusion is that our old hydronic system runs "low and slow," which is good for even heating. I'm not advocating for you to switch from steam to water, but if you did, I think you'd find that the heat distribution can be quite even in these old cast iron radiator systems.

SteamingatMohawk

Interesting. Thanks.

leonz

Closed loop geothermal can become very expensive in installed cost as you have to drill deep with a single bore hole in order to gain usable heating and cooling tonnage. The loss of refrigerant and lubrication oil from the compressor can cause a number of issues with a water to air or water to water closed loop, open loop or semi open loop geothermal system.

The air to air heat pumps are expensive to repair if a circuit board becomes fried for whatever reason.

The so called "thermally enhanced" grout is clay which is a net insulator, please do not let anyone tell you differently-mason sand pumped in the bore hole around the drop pipe will always be a better heat exchange method with or without steel well casing.

About your boiler, when was the last time it was flushed out and the mud cleaned out of the boiler sump?
has the pig tail ever been cleaned? I think your boiler needs some TLC, the header pipes in the basement should be checked for the proper slope, the radiators checked for level to assure they can drain back and return and the radiator vents cleaned or replaced if needed.

Does your boiler have a drop header or a double drop header to provide dry steam?

After the TLC perhaps the best solution is to use trv's to reduce the problems you have after covering all the bases with cleaning the pig tail(s), skimming the boiler water and wanding the boiler sump to clear it of mud, checking the header pipes for proper slope, checking the radiators for the proper slope for draining back and or adding a drop header or double drop header to the boiler for dry steam and adding trv's to better control the temperature.

EBEBRATT-Ed

@leonz

Unlikely to be a boiler or piping problem if the system has been working ok for years.

Converting to hot water is an option. As @jesmed1 mentioned you probably over radiated as is.

I have a 1920s house I do a little work in for my nephew that had a steam vapor system and someone else converted it to hot water about 20 years ago. Works fine.

But I would take another shot at the steam first. Start from square 1 and look at the basics.

1. Run the boiler and watch it carefully on a long call for heat. Make sure the LWCO and pressure control are not interrupting the cycle when they shouldn't be. Make sure condensate is coming back as the steam goes out.

2get the mains to heat to the end of the mains as quickly as possible and that the mains get heat to the ends about the same time.

3. then take on the radiator vents. Rad vents has an effect on #2 above. balance the system as much as possible. See how that goes

jesmed1

I'd also take another hard look at the way the new tenant is using the living room, and how much time he spends in there near the thermostat. The human body is giving off around 100 watts are rest. Add a few high-wattage lamps, TV, VCR, and it's not hard to have 500 watts of "passive" heating of that room. And it doesn't take much passive heating in a small room to throw off the thermostat and increase the time between heating cycles.

ChrisJ

jesmed1 said:

I'd also take another hard look at the way the new tenant is using the living room, and how much time he spends in there near the thermostat. The human body is giving off around 100 watts are rest. Add a few high-wattage lamps, TV, VCR, and it's not hard to have 500 watts of "passive" heating of that room. And it doesn't take much passive heating in a small room to throw off the thermostat and increase the time between heating cycles.

This is going to sound sarcastic, it's not.
What exactly is a "high wattage lamp" these days?

Years ago it would be a few 100-150W bulbs.

jesmed1

ChrisJ said:

jesmed1 said:

I'd also take another hard look at the way the new tenant is using the living room, and how much time he spends in there near the thermostat. The human body is giving off around 100 watts are rest. Add a few high-wattage lamps, TV, VCR, and it's not hard to have 500 watts of "passive" heating of that room. And it doesn't take much passive heating in a small room to throw off the thermostat and increase the time between heating cycles.

This is going to sound sarcastic, it's not.
What exactly is a "high wattage lamp" these days?

Years ago it would be a few 100-150W bulbs.

LOL. Yes, 2-3 lamps with 100 watt bulbs near the thermostat might be enough to throw it off. Maybe @SteamingatMohawk just needs a boxful of free LED bulbs for his tenants? (Yes, I'm joking, but you never know...)

I know it sounds slightly ridiculous, and the heat contribution from lamps, etc may turn out to be trivial. However, we did have a similar problem in our 4-unit condo building. The thermostat for the 2 units on our side of the building is in our downstairs unit, and sometimes the upstairs unit was getting cold. I finally figured out that the natural gas direct vent heater we were using on the back porch was putting out enough BTU's to waft all the way from the back of the condo unit to the front, reaching the dining room where the thermostat is, and heating the dining room just enough to delay the heating cycle longer than normal. Meanwhile the upstairs unit continued to lose heat, until it cooled 2 or more degrees below the Tstat setpoint.

Once I realized what was happening, we started closing doors so that the auxiliary heat from the back couldn't draft through the hallway into the dining room and throw the Tstat off, and that fixed the problem. The boiler ran more often, and the upstairs stayed 68-70.

mattmia2

Probably the best thing would be to put TRVs on the radiators(on the vent of one pipe steam so it doesn't vent at the start of the cycle, can't stop it from heating once it starts until the cycle ends) or at least on radiators in areas that are prone to overheating and use it to keep those radiators from heating some cycles.

I would look for a system that lets you put a temp sensor in each apartment and has some sort of logic to just ignore one that is way off.

Jamie Hall

I've thought a good deal about this situation, @SteamingatMohawk -- in between other things (Christmas season tends to have a lot to think about and work on!).

I think, all things considered, that your best bet will be a multi-step program.

First, make sure your mains really are vented well.

Second, go around and adjust the venting on the various radiators so that the heat is fairly even. The calculated vent sizes are a fair place to start -- but are unlikely bot be what you end up with.

Third, figure out a neutral place in the building which does get heated by the steam, but is hopefully not a place restricted to just one tenant, and then put the thermostat there and lock or secure it.

Then, and last, set that thermostat to some legal but low temperature -- let's say 60 for starters -- and install four newer air to air minisplits, one for each apartment, and let the tenants have at it. If they have individual electric services, so much the better. Some of the newer ones work well enough, even down to 0 or so.

That way, if you have a fresh air fiend or someone who likes it in the 80s, he or she gets to spend as much as they like and neither you nor the rest of the tenants suffer.

SteamingatMohawk

Lots of things to look at, thanks.

Regarding TRVs, I wondered about them for several years, but concluded they could only help in overheating and dropped the subject. Additionally, 6 of the radiators are under windows near the corner of the room with a door (Hinge side) about 9 inches away from the corner on the perpendicular wall. It doesn't seem like a location where I would get a "representative" reading of the whole room.


I don't see any movement in the piping in the basement, so elevations seem to be OK.vPlus, when the heat comes on there is plenty to go around. I am finishing up doing the calculations from the Gill/Pajek report and think I have as close as I am going to get volumes for the radiators. The results are a bit surprising, but I need to make extra sure I didn't mess anything up before I post the results.

Jamie Hall

In my not so humble opinion, TRVs on one pipe steam are really problematic unless there are a lot of units and the boiler is run off a heat timer or something of the sort -- and sized at the minimum, on the theory that there will rarely be a time when all the TRVs are open at once.

mattmia2

there are remote heads and sensing bulbs available for TRVs. You wouldn't want to put them on all, just a strategic few.

SteamingatMohawk

@mattmia2 Do you have any specific examples?

mattmia2

SteamingatMohawk said:

@mattmia2 Do you have any specific examples?

All the TRV systems have similar remote actuators.


https://supplyhouse.com/Macon-Controls-MAC-EVOL-EVOLZ-Remote-Dial-and-Sensor-Operator-3021221

https://supplyhouse.com/Macon-Controls-MAC-EVO-Z-Direct-Mount-Thermostatic-Operator-with-Remote-Sensor-66-Capillary-3025802

ChrisJ

Jamie Hall said:

In my not so humble opinion, TRVs on one pipe steam are really problematic unless there are a lot of units and the boiler is run off a heat timer or something of the sort -- and sized at the minimum, on the theory that there will rarely be a time when all the TRVs are open at once.

I have TRVs on 5 out of 10 single pipe radiators and I don't think I've had any issues with them other than the vents needed to be reasonably balanced.

Other than that, a thermostat set to 2 CPH will do wonderfully.

They will not fix a broken system, or stop a radiator from heating that is already receiving steam.
But they will slow one down from progressing, or totally stop it from heating during a cycle from the start easily.

What problems have you seen Jamie?

Jamie Hall

The two biggest problems I see with them are to some degree preferences, not problems so much The worst is that they can aggravate a cycling problem in a boiler which is oversized. This depends somewhat on how "organized" they might be -- and might be worse if they are sort of coordinated, as they might be in an apartment type setting, where all the TRVs in one apartment might be closed at once -- if there are only four apartments, problem. If there are 40, no big deal.

The other is that to maintian control the boiler has to shut down and drop to zero at moderately regular intervals -- as you note, they cannot shut off a radiator which is already receiving steam. They can only prevent a radiator from heating if they are closed at the beginning of a cycle (this is for one pipe -- two pipe on the valves they always have control). This is easy enough to cope with -- just make sure that the boiler turns off long enough from time to time, but that's not always an easy trick to do.

SteamingatMohawk

I looked at the remote sensors and was not surprised the sensor is connected to the actuator with a 6'-6" capillary tube. With most radiators under a window in corners (TRV toward the corner) with a door on the adjoining wall, it doesn't seem practical to use these devices.

I wonder if someone in the steam heat industry is working on a true wireless TRV design.

Hey, @ChrisJ, this is right up your alley...

SteamingatMohawk

I'm beginning to think the imbalance between the tstat living room and the living room below it is affected by

the difference in venting rates I have set for both radiators,

potentially complicated with the possibility of drawing a vacuum during the shoulder seasons

and when the boiler firing time probably wouldn't be for a long period and

the off time is extended because of the "balmy" outdoors.

But I still fall back to the last 4 years with no complaints.

mattmia2

There are 24vac actuators for TRVs as well but the type with the capillary is much more practical for most applications.