Thermostat or pump? Temporary Fix?

tommyello

Hi all, I have a beautiful Weil-McLain steam boiler, kind of looks like a big whisky still but only produces steam. Model 40-PIDN, Series 5.

It's a few years new, services all the cast iron radiators in my house and works well.

I have one circulated hot water line that goes to a new constructions spare bedroom and this is what my question is about.

This room has a thermostat and it is not working to turn off the circulated hot water. It's nice, the room is always warm - sometimes 75 degrees so it's very cozy in the winter but I feel I am wasting a lot of heat when no one is using that room.

I reset the thermostat a few times - no luck.
I'm thinking to replace the thermostat but somehow I don't think that will fix it either.

My hesitancy in calling a professional lies with the experience with my previous boiler which was not installed properly.

The line in this room never worked until we had the boiler serviced and they said when the water level gets low it can cause all the water to flow into the basement and then the water has to be pumped up to the second floor to get it working again.

They replaced the pump and approx. $700 later it was working.

The boiler went low at some point again. I don't think they changed the pump but the bill was close to the previous repair. As I understood it they had to get a pressurized line and pump the water back up to the first floor.

Now that my new boiler is installed properly, the way the pipes are organized as it was explained to me, the water will never empty out of the circulated hot water lines - great!

Now I don't worry about a cold room but now it's warm all the time and maybe I'm spending money heating it when I don't have to.

It's obviously something electrical. There is a small pump that I guess moves this water and it's not getting the properly stimulus to turn off.

Like I said, i've reset the thermostat a few times. I have also completely turned off power to the boiler and turned it on again, hoping to reset it. No luck.

I was thinking that maybe I could turn the shut off on that circulated line to stop the water from circulating. It's just a thought, I won't do it because I'm sure I'll make more of a problem.

neilc

post a picture or 2,
showing the boiler, circs, and heat exchanger, floor to ceiling, all in one shot,
from a couple angles,

can you tell that the room thermostat is turning off the circs?
zoom in on the room circ, its label, does it have a check valve?

are there isolation valves to the room?
isolate until the room rad cools down, shut off the boiler, open the room isolation with the boiler off, do those pipes and rad heat back up? heat syphon?

Jamie Hall

Do I take it that this hot water radiator is on the second floor? And there is a circulating pump which takes water from the boiler and pumps it up to the second floor, and then it comes back down to the boiler?

That is a very iffish arrangement. Not that it can't be made to work -- it can and obviously does -- but the problem (as you have discovered) is that if the boiler water drops below either connection to the boiler when the pump stops the water will drain out of the high level piping, and the pump would have to be able to generate enough pressure to fill it back up again.

This the average circulator can't do. It can keep the loop running, yes, but only so long as it is full of water and both ends of the loop are below the boiler water level.

There are three solutions to the problem. The first is to make sure that the inlet from the boiler to the pump is well below the water level in the boiler, and then select a pump which has enough pressure to pump water from the boiler up to the top of the loop. The second is to relocate the connections at the boiler so that neither of them can go below the boiler minimum water level, and provide a means to fill the loop with water (prime it). Several ways to do that, none of them automatic. The third is to interpose a heat exchanger with the boiler water being circulated through one side of the heat exchanger and the upstairs loop through the other side, which would be pressurised just like any regular hot water heating system.

mattmia2

Are you sure the circulator is running? My guess would be that there is gravity circulation happening and it either needs a flow check valve or there is one and it is stuck open.

Intplm.

You say you have a steam boiler.
You are then using the condensate from the boiler too heat a space.
Depending on how comfortable you are and how handy you are you can try this.
Make sure the circle is running.
Then.
Remove the t-stat from the wall and disconnect the wires.
Look to see if the circle is still running.
Now twist the wires together, or jump the wires out. (Small spark and possibly a very small tingle.) If the circle starts up again it just might be the T-stat needs to be changed.

And what @mattmia2 says above.

tommyello

Jamie Hall said:

Do I take it that this hot water radiator is on the second floor? And there is a circulating pump which takes water from the boiler and pumps it up to the second floor, and then it comes back down to the boiler?

That is a very iffish arrangement. Not that it can't be made to work -- it can and obviously does -- but the problem (as you have discovered) is that if the boiler water drops below either connection to the boiler when the pump stops the water will drain out of the high level piping, and the pump would have to be able to generate enough pressure to fill it back up again.

This the average circulator can't do. It can keep the loop running, yes, but only so long as it is full of water and both ends of the loop are below the boiler water level.

There are three solutions to the problem. The first is to make sure that the inlet from the boiler to the pump is well below the water level in the boiler, and then select a pump which has enough pressure to pump water from the boiler up to the top of the loop. The second is to relocate the connections at the boiler so that neither of them can go below the boiler minimum water level, and provide a means to fill the loop with water (prime it). Several ways to do that, none of them automatic. The third is to interpose a heat exchanger with the boiler water being circulated through one side of the heat exchanger and the upstairs loop through the other side, which would be pressurised just like any regular hot water heating system.

I may not have explained the setup in enough detail.

I have two Emerson thermostats. One controls heat/steam to the whole house. The other just for one room, so, two zones I guess you would say.

My new steam boiler (about three years old along with the thermostats) is located on the floor of the basement. Pipes ring about a foot below the basement ceiling and then run throughout the house to 1st floor and 2nd floor to cast iron radiators.

There is a Taco Cartridge Circulator 007-SF5 on the back of the boiler. A pipe runs up from that to the extra room and the hot water circulates through a baseboard.

Since the boiler is in the basement, lower than all of the other pipes it's feeding steam or water to, this might then not apply to some of the solutions outlined. I appreciate your input. My house was built, If I am to believe a plaque affixed to the outside, in the 1840s but everything is nice and clean and well built.

neilc

if only we could see this , , ,

tommyello

Intplm. said:

You say you have a steam boiler.
You are then using the condensate from the boiler too heat a space.
Depending on how comfortable you are and how handy you are you can try this.
Make sure the circle is running.
Then.
Remove the t-stat from the wall and disconnect the wires.
Look to see if the circle is still running.
Now twist the wires together, or jump the wires out. (Small spark and possibly a very small tingle.) If the circle starts up again it just might be the T-stat needs to be changed.

And what @mattmia2 says above.

Thanks for this feedback and observation. This sounds like the pro way to test the t-stat, I thought by simply resetting it it might fix itself but this sounds a bit more sound to determine if the problem is with the T-stat.

tommyello

mattmia2 said:

Are you sure the circulator is running? My guess would be that there is gravity circulation happening and it either needs a flow check valve or there is one and it is stuck open.

Yes, condensate is heating this room. I think this might be the issue, something is stuck open or not running.

I'm not certain how to tell if it's running. When it's operating (like now) I guess I could go down to the boiler and maybe hear something spinning off the Taco or some other sound. I have not done this.

Jamie Hall

OK. And presumably a pipe comes back down from the basement and connects to the boiler somewhere? This doesn't sound like a condensate system, by the way -- it sounds like a straight boiler water system.

Problem is. If for any reason the boiler water is low enough to be below either the pump or the return connection -- wherever that is -- the upper piping will drain, and the pump simply isn't big enough to refill it. Enough flow, yes. But not enough head.

tommyello

neilc said:

if only we could see this , , ,

tommyello

Jamie Hall said:

OK. And presumably a pipe comes back down from the basement and connects to the boiler somewhere? This doesn't sound like a condensate system, by the way -- it sounds like a straight boiler water system.

Problem is. If for any reason the boiler water is low enough to be below either the pump or the return connection -- wherever that is -- the upper piping will drain, and the pump simply isn't big enough to refill it. Enough flow, yes. But not enough head.

I see, so outside of the t-stat, sounds like my best bet will require a qualified plumber to get everything circulating properly.

When this new boiler was installed I was told the way it was piped it would not all drain down to the first floor and I think this is correct because in the old boiler, when the water would drain to the basement, the room with the baseboard would go cold - no heat.

There definitely is circulation and the room is warm. However, if I set the t-stat to 68, the room might get as warm as 75 or something like that.

Sound like the best bet is a qualified plumber to get everything in sync again.

Jamie Hall

See if you can get whoever did the boiler -- looks like they did a decent job of it.

tommyello

Jamie Hall said:

See if you can get whoever did the boiler -- looks like they did a decent job of it.

Yes, I think they really did a great job (though I am a web designer/developer by trade and couldn't tell you if it really is a good job) I sensed when they were working on it that they were putting this together with great care and gave us a lot of education of how it worked and why the previous one, while it did heat the home, was faulty in some of the way it was set up.

neilc

can we see under the cover of the Taco

looking at the LED as you posted, the circ should not be running,

and with 2 flow checks, no heat syphon

tommyello

neilc said:

can we see under the cover of the Taco

looking at the LED as you posted, the circ should not be running,

and with 2 flow checks, no heat syphon

Do I have to remove something on the Taco or just the label you wish to see?

MikeAmann

Is this thumbscrew in the bypass position?

neilc

cover off so we see the wires inside

tommyello

neilc said:

cover off so we see the wires inside

Got it, thank you. Anywhere I see 'Warning..' written on the cover I tend to stay away. Looks like only 1 screw, I will see what's under there and get a photo.

tommyello

MikeAmann said:

Is this thumbscrew in the bypass position?

Here is a close up of that particular component. I have never touched this. It's possible I may have opened up the ball value on the end at some point for no reason at all.

This system was working fine until some point last season but because it wasn't so cold it didn't really matter much. Not sure what may have changed to cause it to not turn off.

tommyello

tommyello said:

neilc said:

cover off so we see the wires inside

Got it, thank you. Anywhere I see 'Warning..' written on the cover I tend to stay away. Looks like only 1 screw, I will see what's under there and get a photo.

Here is under the cover.