Converting from steam to hot water in a rental

Nw1351

Hi, longtime lurker, first time poster. 

I have a rental 3 hours away from me with one-pipe steam heat.
The piping is all 95 years old now, as are most of the rads. Stuff has been leaking for years, and tenants never tell me, so I have blackened floors and rot around the radiator piping. 

Summary: I have easy access for plumbing to every room, and intend to put in baseboard radiators, and cut the house to 3-4 zones. 

Other than the history and how steam can be made to work, is there any better reason to keep steam? 

Nw1351

Here's more reasoning;
I can easily do the work myself, and the boiler is compatible with hot water or steam. 
I can zone hw. 
I can control and monitor it with microprocessors. 
I can fix a hot water system fast, and most techs can as well.
Hw is quiet.
Hw baseboards will not burn a child or break his head (lots of stitches for my son once, after whacking his head on a cast iron beast in his room). 
Leaks on new piping are less likely than leaks on old.

Steam has been incredibly inefficient as well. 
I lived in the house for 13 years myself, and could never get the steam to run more efficiently or heat the house quickly,, evenly, or not constantly overshoot. 
Techs rarely know what they're doing, and I suspect the new boiler wasn't even installed properly for steam. 

The house has modern windows, a lot of new insulation, and double thickness sheetrock walls and cielings in every room. 

The boiler is a few years old, but basically new.

The boiler runs almost constantly, and the basement is sometimes warmer than the house.

I replaced several rads over the years, and they look great, but are not worth the higher maintenance overhead. 

LRCCBJ

Your only issue is whether the 95 year old piping in the walls will hold 20 psi without leaks. Other than this issue, the HW system will definitely be more efficient and less troublesome for the owner.

Before I made the commitment, I would attempt to pressure test it.

Nw1351

I'm going to run new piping to new baseboard rads. The access to the first floor locations is super easy for copper or pex. The 2nd floor a little tougher, but not bad, I actually put 2" conduit from basement to 2nd fl when I was replacing the walls 20 years ago, and though not kosher, I could run pex up it along with the cat5 and obsolete rg6 (tenant's boneheaded cable guy stapled rg6 to the walls anyway). I may actually cut the ends off the black iron steam pipe for 2 rooms, and feed pex-al through it to start and finish the 2nd floor zones. Anyway, all that to say, the steam pipe won't be used for fluids or pressure in this conversion. 

Thanks for the input, helps me commit.  

mattmia2

the steam is much more even, comfortable, and quiet if it is working right. leaks that have been happening for years are a lack of maintenance. it will happen with any other system if the landlord isn't inspecting stuff periodically. the only above water line leaks should be valves and vents and such, the piping shouldn't rot out unless the system isn't functioning properly and is putting a lot of water in to the piping.

Steamhead

mattmia2 said:

the steam is much more even, comfortable, and quiet if it is working right. leaks that have been happening for years are a lack of maintenance. it will happen with any other system if the landlord isn't inspecting stuff periodically. the only above water line leaks should be valves and vents and such, the piping shouldn't rot out unless the system isn't functioning properly and is putting a lot of water in to the piping.

This.

Where is the property located? We might know someone who can look at this and give you some answers that actually mean something.

Jamie Hall

As several have implied, all of your problems with the steam system -- both as a rental and when you were living there -- are due to poor or non-existent maintenance. Sorry about that.

It isn't quite fair to attribute them to being steam heat, now, is it?

Steam is neither less nor more efficient that hot water, in general -- given similar levels of care and maintenance

That said, hot water is a little easier to understand and maintain, up to a point. However, it also needs maintenance and attention -- and poor maintenance with hot water can be quite equally detrimental, with the added benefit of floods as well as drips.

OK. Enough of that. Where are you located? If you are going to the trouble of discontinuing the steam, I suggest you investigate the possibility of installing a heat pump system. While it won't be any less maintenance sensitive (in fact, it will be more) it might be less expensive to run, depending on what your electricity rates are.

Nw1351

It's on Long Island, in NY.

20 years ago, plumbers/hvac that specifically advertised steam work were closer to NYC and travel surcharge was a deal breaker. I'm sure that hasn't gotten any better for old systems. And I'm sure like any skilled specialty, it will cost more, increasing the general cost to keep the system. 

It was very well maintained when I lived there, but would still take a long time to heat, and then often overshoot. Literally chased it for years, but the nature of steam is that it's very difficult to set-and-forget, which is what I need for a rental. 

Re: efficiency 
It seems rational that getting water to temp to produce steam will use more energy, and maintaining that higher temp to steam will be where efficiency is only slightly worse than maintaining at the lower temp of HW. But the wasted energy of overshoot heating is still lost energy in the end. 

Jamie Hall

It is NOT the nature of steam to be difficult to set and forget. Period. There are many many steam systems which are set to hold a temperature and do so, within a degree or less, all winter with no more than a passing glance at the thermostat.

The problem with overshooting is one of the thermostat, and is not inherent to steam. I agree that overshooting is inefficient -- but blame the thermostat, not the rest of the heating system. It will overshoot just as badly with hot water as it will with steam, for the same thermostat.

It does take more energy to create steam than it does to create hot water. However, steam transferred to a radiator releases more energy to the space than does hot water. No difference there.

Now a rental does pose problems -- for any heating system. The best thing to do for a rental is, first, the landlord controls the maintenance of the system. Second, the tenant pays for the energy -- and that holds for any system. If the landlord is paying for the energy, the tenants will open the window, crank up the thermostat, and enjoy the fresh air. On the landlord's dime. As I say -- that is true for any heating system.

Now. Availability of decent craftsmen. Yes, that is a problem. This too is true of both hot water and steam; decent craftsmen are hard to find for either one. Worse, they don't come cheap. They are worth what you pay for them, and in your area I dare say the costs are high.

You'll be better off, in my opinion, to keep the steam and pay a really good person to come and get it all set to rights than to pay a hack to install a hot water system (it isn't just connecting pipes).

hot_rod

Also consider panel radiators if you do make the switch. They are easily zoned with TRV at each radiator. Their heat output is mostly radiant and they are more durable than fin tube.
Properly sized they could run at 120- 130 SWT and allow for a high efficiency boiler to run in the 90% plus efficiency. 1/2" pex homeruns are easiest to retrofit also.

jumper

If you're going to repipe you can also do two pipe vapor steam and use ceiling height panels. Resulting pure radiant heat means comfort at lower air temperature.

Successful boiler conversion to HHW can reduce required maintenance. So can redundant safety for steam.

Zhadanovsky, Igor is on this site and on the web. You can use locked TRVs or orifices to have some control over fuel costs. Ideal set up for rental is undersized hydronic with supplemental electric on tenant's meter.

LRCCBJ

Nw1351 said:

It seems rational that getting water to temp to produce steam will use more energy, and maintaining that higher temp to steam will be where efficiency is only slightly worse than maintaining at the lower temp of HW. But the wasted energy of overshoot heating is still lost energy in the end. 

It is well documented that the higher the temperature of the fluid that is utilized to heat the building, the lower the system efficiency. The reason mod-cons are very efficient is somewhat due to condensation but is much more related to system efficiency. The mod-con loses next to nothing to the basement. Compare that to a steam boiler which will lose a minimum of 12K BTUH to the basement every time it runs. That's a significant loss that very few individuals on this website will understand or admit.

A small conventional CI hot water boiler will also generally be more efficient than steam if it can be run at a lower temperature. This begs your consideration of generously sized panel radiators, as Bob suggested, to enable you to operate the boiler at reduced temps. If you go this route, a mod-con will definitely save a significant amount of energy due to the benefit of condensation for at least 50% of the heating season. The modcon also benefits from modulation whereby it runs at greatly reduced output for 95% of the season (and 100% of the season for most installs that have the maximum output quite a bit greater than the heatloss of the building).

Nw1351

I'd never seen the panel radiators, but a little time on google shows them as very impressive. A 24"x24" is just a little lower btu output than the 5' fin tube I'd planned...more expensive, but maybe more durable, and does sort of keep that old look...I really don't like the look of baseboards, so that helps. 

I have to re-use the steam boiler, converted to HW. I'd love to run at higher efficiency,  but the boiler cost would push the project out of budget. 

Re: steam overshoot; 
I know it can happen with multiple systems, but it seems easier to control with other. I had probably 4 or 5 different t-stats in my time there, and varied their location, but overshoot seems natural without anticipator. I'm maintaining 212+° water until the stat is satisfied. Then the burner stops, but that 212° water doesn't instantly cool...it continues to radiate heat for another x minutes. 


Re: basement heat
Yes, I can't crack that nut. Pipes are insulated, boiler is factory insulated, but just by nature of running for an hour straight, it heats up the basement. Best I can guess is by radiant from.the boiler face and maybe the condensate return piping radiating. 

delcrossv

^^^All good points if it's in your home. But...
The added expense, additional maintenance and lower lifespan of a mod-con makes no sense when the tenant is paying for heat.

Nw1351

BTW, tenant pays energy and I pay for system maintenance. So this is also to help the tenant improve comfort and efficiency. 

And...because my last tenant often had a sad story of choosing between rent or heat. Of course, when I told her to run the stat lower and she said, "you mean like at 70?" I stopped feeling too bad about it... 😄

LRCCBJ

Nw1351 said:

Re: basement heat
Yes, I can't crack that nut. Pipes are insulated, boiler is factory insulated, but just by nature of running for an hour straight, it heats up the basement. Best I can guess is by radiant from.the boiler face and maybe the condensate return piping radiating. 

Think about how much energy is required to heat up the entire basement! Every single BTU of that energy will be lost to the basement walls. Most of it will go out the foundation walls (R value of .8) above ground level. NONE of it will go to the first floor.

Jamie Hall

A couple of comments. I know you won't pay attention, or believe a word I say, but anyway...

It is NOT well documented that the higher temperature of the working fluid leads to lower efficiency -- if equal systems are built and maintained equally well. In fact, that's not documented at all.

Second, it is possible to set up a residential steam system and thermostat such that overshoot, even from very long recoveries (when the problem is worst) can be kept to less than half a degree. Under temperature maintaining operation, it can be kept within the resolution of the a normal thermometer. How do I know? Because I have systems running that way, and have run that way for years.

However, it's always nice to have a real expert set the rest of us knuckle draggers straight -- "That's a significant loss that very few individuals on this website will understand or admit.'

Nw1351

Yeah, when you cited 12k btu, that was pretty troubling... This basement is leaky, dirt floor, with paper thin windows, so no doubt it's bad. That won't be change with HW, but with less burner run time for the living space, there will be less siphoned off by the walls. You may have Aldo just talked me into building an insulated closet around the mechanicals down there now... 😄

LRCCBJ

Jamie Hall said:

A couple of comments. I know you won't pay attention, or believe a word I say, but anyway...

It is NOT well documented that the higher temperature of the working fluid leads to lower efficiency -- if equal systems are built and maintained equally well. In fact, that's not documented at all.

Here is the documentation of outdoor reset which explains the philosophy of utilizing lower temperature fluid for increased efficiency.

https://www.watts.com/our-story/brands/tekmar/references/how-outdoor-temperature-reset-controls-save-energy

This might also help with your understanding of the concept:

https://www.usboiler.net/what-is-outdoor-reset-control.html

Nw1351

But what's the efficiency like in that system? And what's the maintenance cost over time to keep it that way? 

My dad used to be a purist. He'd restore cars and search the world to find an original carburetor for an engine that would guzzle fuel, belch half of it from the tailpipe, and move the vehicle at marginally OK highway speeds. My neighbor collects classic cars, and took us out in an all original '57 caddy once. 
It moved that car from point A to point B comfortably. But when he shut it off and tried to start it again, it vaporlocked. That was the last straw for him, and he put an LS in it, and drives it whenever he wants without ever worrying about shutting it off. 


Whether it's well documented or not, it's rational and logical that raising the temperature takes energy input, so raising it over 212 and keeping it there takes more energy than raising it to 180 and keeping it there. 

I know the assertion is that my steam system is just not set up right, but it would seem logical that if the system is so difficult or requires niche expertise to get set up right, it's probably not the right system for the situation going forward. 

A small part of me was hoping to get out of the work...but it's like it's confirming that it's exrra work and money to maintain an obsolete system. 

LRCCBJ

Nw1351 said:

Yeah, when you cited 12k btu, that was pretty troubling... This basement is leaky, dirt floor, with paper thin windows, so no doubt it's bad. That won't be change with HW, but with less burner run time for the living space, there will be less siphoned off by the walls. You may have Aldo just talked me into building an insulated closet around the mechanicals down there now... 😄

If you are going to keep the CI boiler, try to keep the SWT down. If you can run it at 150F supply rather than 180F, the savings are significant. It all depends on the size of the radiation that you install.

pecmsg

Nw1351 said:

It's on Long Island, in NY.

20 years ago, plumbers/hvac that specifically advertised steam work were closer to NYC and travel surcharge was a deal breaker. I'm sure that hasn't gotten any better for old systems. And I'm sure like any skilled specialty, it will cost more, increasing the general cost to keep the system. 

It was very well maintained when I lived there, but would still take a long time to heat, and then often overshoot. Literally chased it for years, but the nature of steam is that it's very difficult to set-and-forget, which is what I need for a rental. 

Re: efficiency 
It seems rational that getting water to temp to produce steam will use more energy, and maintaining that higher temp to steam will be where efficiency is only slightly worse than maintaining at the lower temp of HW. But the wasted energy of overshoot heating is still lost energy in the end. 

Where on the Isl of Long?

Nw1351

pecmsg said:
Where on the Isl of Long?

Just realized I can quote...
It's in Huntington, right around the middle of the island. 

Jamie Hall

OK. "Whether it's well documented or not, it's rational and logical that raising the temperature takes energy input, so raising it over 212 and keeping it there takes more energy than raising it to 180 and keeping it there. "

This might be true -- if you were just storing the heated fluid. But you are not. You are using that heated fluid to transfer heat from one point to another. The loss there -- and there is one -- is in the heat lost in the pipe work or ducting carrying the heated fluid. If one is being quite precise, that is a measurable -- but relatively minor loss, but is one of the reasons why any piping or ductwork should be insulated.

The other, related fallacy is that that heat loss from the piping or duct work is actually a loss. Unless the piping or ductwork is outside the heated envelope, it is not a loss for the overall system.

It can be debated how much of a problem the direct heat from the boiler and any breaching is in a basement or furnace room. That depends, like the heat loss from piping or duct work, on the relationship of that space to the heated envelope. In the case of a medium size boiler -- say a Weil-McClain 580, the direct heat from the boiler to the boiler room will be around 8,000 BTUh, or somewhere around 2% of the total boiler output.

A condensing boiler can reach a significantly higher overall efficiency, since it is also recovering the latent heat in the water vapour from combustion. This, however, is only effective if, in fact, the flue gas temperature is reduced to well below 140 F, which requires low return temperatures from the system. As noted, large panel radiators are a good match, as are radiant floors.

In this application and in your geographic area, if you can install enough panel radiation to utilise 120 F water at your design conditions, I very strongly recommend that you investigate -- and install -- an air to water heat pump rather than another boiler.

Jamie Hall

PS -- I am a purist about classic and older cars, by the way... again, proper and careful maintenance and adjustment. They are more difficult to maintain -- or rather, I should say, they require a good deal more skill to get them performing well and keep them that way. That said, by '70 C10 gets just as good mileage as a '24 half ton with similar performance -- and I can fix it if need be with a screwdriver and , a of wrenches, and a dollar bill... and drive it home to where I can do it right.

LRCCBJ

Jamie Hall said:

In the case of a medium size boiler -- say a Weil-McClain 580, the direct heat from the boiler to the boiler room will be around 8,000 BTUh, or somewhere around 2% of the total boiler output.



The heat transfer is governed by this formula:

q=U A dt

U is the constant for cast iron to air. There is some variability here but 5 is a reasonable number.

A is the area. A 580 is a very large residential boiler. 623K input! 35 square feet of CI exposed to air.

dt is the temperature difference between the CI and the surrounding air. Figure 160 on a CI steam boiler that maintains a temperature of 212F while operating.


The result is 28000 BTU/hr!! 4.5% of its input is lost (presuming no insulation on the jacket).

No small wonder the basement is warm!

Jamie Hall

Except the jacket temperature is nowhere near 212. Try a bit over 100, at least by my thermometer (and a hand leaning on it agrees). That's called "insulation".

LRCCBJ

If you believe that the overall jacket is capable of keeping the total exposure at 100F to the basement, the loss would be as you predicted. I am doubtful the insulation is that efficient. Most basements wouldn't even notice 8K.

Jamie Hall

It's not that I believe it, it's that that's what I observe...

LRCCBJ

Think about the flue pipe. Say 10' of 7" S/S pipe with a DT of 400 F

The above formula with U=3.5 gives a heatloss of 25K BTUH. Significantly greater than the boiler itself!

Jamie Hall

As I said above, in your application and with your mindset, I would strongly recommend an air to water heat pump with enough radiation to use 120 degree water on the design day.

EBEBRATT-Ed

I would go for HW. Easily zoned and less problems. Steam is fine but it is a hands on system. If your 3 hours away hot water is the better choice.

Of course steam can be made to work fine....with the right mechanic which are harder and harder to find.

If you lived in the house and were handy fixing the steam could probably be done for less $$.

It also take time to get steam balanced and working properly.

Steamhead

Nw1351 said:

It's on Long Island, in NY.

20 years ago, plumbers/hvac that specifically advertised steam work were closer to NYC and travel surcharge was a deal breaker. I'm sure that hasn't gotten any better for old systems. And I'm sure like any skilled specialty, it will cost more, increasing the general cost to keep the system.........

No longer true. Go here, you'll find some of the best in the business:

https://heatinghelp.com/find-a-contractor/state/NY/

hot_rod

There have been studies on efficiency gains via lower boiler operating temperature. This is the basis of outdoor reset controls, they just monitor and reduce boiler SWT

Here is info from Viessmann, probably find the study they quote with some digging.

You will be limited on how low you can run a conventional cast boiler, 155, maybe 150 running a 20 delta.