House getting too warm!

Hugh_Slater

This is an unusual problem, I know.

We have an older brick home with a steam boiler that also feeds a hot water loop. We have lived here for about 6 years and have had some problems, primarily with the hot water loop. We replaced the circulator pump not long after living here. More recently, we noticed water on the floor by the boiler and called a contractor who said the water limit had failed and filled the entire line with water. Not long after, the mother board blew and had to be preplaced.

So, there have been a few issues. But since replacing the mother board, we have had trouble getting the hot water loop back up properly. The loop is on a separate thermostat covering a two floor addition. I did manage to get it heating but now all of the other zones heat up before the addition gets to temperature. So our main thermostat is set at 70 but the temperature never drops below 74. I turned down the water loop thermostat to 64 but it still won't get down to 70 in the main rooms. I also tried throttling open the bypass valve (on a copper line around the boiler) which seems to have helped some but we are still wasting energy and not comfortable.

Any suggestions? I would like to keep the addition at 68 and the house around 70 but so far can't balance it. Also having trouble getting someone over here to look at it.

BDR529

You got a older steam system with a hot water loop that has a mother board.

Before you reinvent the wheel...

If you got those cheesy round Honeywell t-stats, NOT the mercury switch but the one that took thier place, the electronic ones. (T-87F?) They seem to have a 15 degree delta I've seen upwards of 20

Jamie Hall

Have you any idea how the loop is controlled? In principle, the thermostat for the loop should turn on the circulator pump. And that's all that turning on the thermostat should do. At some point, there is a switch called an aquastat, which may be on the pipe coming from the boiler to the pump or in the boiler itself, which should turn on the boiler's burner -- but only if the water in the loop needs heat.

I'm not quite sure to what your plumber was referring when he said the water limit had failed. There should be a low water cut off and possibly an automatic water feeder on the boiler -- but they have nothing to do with your hot water loop.

Water on the floor near the boiler is not a particularly good thing, though, and it is possible that he was referring to the automatic water feeder, which could have overfilled the boiler.

Nor am I quite sure to what "mother board" you are referring.

Can you clarify those two points?

And can you check your controls operation? As I say, turning on the hot water loop thermostat should turn on the circulator pump -- not the boiler. The boiler may come on, however, but only if the boiler water isn't hot enough. If it comes on right away with the thermostat and stays on so long as that thermostat is calling, it's miswired.

Hugh_Slater

I brought up two things that are confusing the discussion--the auto water feeder and mother board issues have been corrected--just bringing them up since we 've had a lot of issues keeping this house comfortable. Lot's of expense on top of our annual maintenance and frequently no heat when it's pretty cold here (like now). The mother board is how the contractor described it--we lost power to the thermostat and it was caused by the control on the boiler which had to be replaced. Again, I don't think this is causing our current issue.

Jamie, you asked about the water loop control. I believe this thermostat does just call for the pump to come on. But the boiler is firing frequently even though the main thermostat is not calling for it. I'm guessing it's either a problem with the aquastat or it's mis-wired.

There is also a loop around the boiler with a throttling ball valve. When it's closed it sends water from the loop back into the boiler. When it's open it sends the return water around the boiler and back to the pump. I'm thinking if it's closed, too much cold water goes back into the boiler and it fires too much. But if it's too open, does the aquastat kick on and the boiler fires too much?

I'm sweating...

HVACNUT

Can you post some pics of the boiler and area? Different angles from about 8 ft away. Different contractors do things different ways so it will help to see your specific setup. 

mattmia2

Is the boiler gas or oil? I suspect the "mother board" is the combustion control for whichever it its.

I suspect it has everything to do with your current problem, when it was replaced the lower temp aquastat for the hot water loop likely got miswired so it is now running on the pressuretrol for the steam side when you have a hot water call so the boiler is coming up to steaming temp instead of just supplying sub steaming hot water to the hot water loop.

Hugh_Slater

Hugh_Slater

MattMia2--It runs on gas.

Jamie Hall

Pay attention to what @mattmia2 said -- I think he nailed it.

Hugh_Slater

I'll take a close look at the wiring and possibly post a pic. If anyone can walk me through how to wire it correctly or where to a get a wiring diagram, I may be able to fix it.

Thanks to everyone for looking at it!

Hugh_Slater

A couple of quick observations--
1, there is a lot more going on in the wiring than I would have guessed. Pics to follow.
2. The burner kicked on while I was down there and I noticed the pump was on too. The main house (steam) thermostat is set at 70 but temp is 74. The water loop kicked on BOTH the burner and circulator pump. Stayed on for a few minutes and then both went off. I could hear the steam start rising through the main house. I had my wife up the thermostat in the addition to double check and both kicked back on again. Thermostat set at 64 in addition (too cold) and rest of house is 75 with the whole house fan on.

Hugh_Slater

Hugh_Slater

There's way more going on here than I would have guessed. Not sure I can tackle this one solo.

There are two thermostats (plus one for the AC which shouldn't connect here at all). I'm not sure why there are so many connections.

motoguy128

The “mother board” is probably just the Honeywell ignition control it has nothing to do with the pumps. Those are controlled by a relay that on the wall, and the call from that zone thermostat should also call the boiler in series with the White Rogers aquastat (the taller rectangular box sticking out the size with a temperature small dial). Its sort of in the wrong location (should be directly on the boiler) and set really low, which is why its not heating that one hot water loop enough.

motoguy128

I looked at the pictures. The aquastat it appears is wired independent of the zone thermostat calling the pump it appears. SO it will cause the boiler to fire independent of the pump running. That’s not the right way to do it. The call from the hot water zone to the pump relay should also call the boiler, but with the aquastat in series. That aquastat should be set to about 160-180 and I would insulated that section of pipe. When its colder out and its been steaming it will deliver hotter water anyway.

But hard ot really make sense of it all just from the pictures.

mattmia2

Is that relay in the boiler connected to anything?

Jamie Hall

I have a rather intense dislike of spaghetti style wiring. But @motoguy128 is quite right. That relay should be controlled by the water loop thermostat, and should turn on the pump. It also, through a separate set of contacts in series with the aquastat, control the boiler. When the steam thermostat calls, that's an independent circuit.

I suspect when your technician replaced the "mother board", he got the wiring wrong -- and needs to come back to fix it right.

And tidy up the wiring at the same time.

Hugh_Slater

While not shocked by the suggestion, I think I want someone who understands this better to do it. He didn’t seem familiar with the hot water loop and suggested we put in a separate hot water heater entirely. 

Know anyone good in Cleveland Ohio?

thanks again for taking the time to look at it. 

Jamie Hall

@gerry gill .Assuming he's still in business, one of the best.