Radiator heating when it's not called for

SDAV

First time homeowner, knew nothing about boilers but I've since been reading a lot to attempt to troubleshoot my issue. I'll try to give as much information as possible, please let me know if you need more.

I have a 2 story home with hot water radiators. There is a thermostat on each level. The baseboards on my main level, one in particular, stays warm even when the thermostat shouldn't be calling for heat. It will heat our home a few degrees above what the thermostat is even set at. It always seems to settle around 72-74 (we set it at 68). I believe it is all of the baseboards on the main level that are staying warm, but I mostly notice it in the living room where the largest section of radiator is. That one has historically gotten a little warmer than the rest as well.

From what I can tell we have circulator pumps on the return side, and flow check valves on the supply side. From my reading it seems like an issue with a flow check valve. Examining them, one of them had a nut that was a few mm up so I tightened it down. This didn't seem to have any effect. What steps should I take next to trouble shoot? Am I missing something? Thanks for any help.





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Alan (California Radiant) Forbes

Are both of those Taco Flow-Checks in the down position? Sometimes, someone will raise the weighted check via the knurled dial and leave it in the up position which will allow gravity flow.

There might also be some debris in the Flow-Checks to prevent the weighted check from closing all the way.

You might also be getting flow up through the return, through the pumps.

SDAV

Alan (California Radiant) Forbes said:

Are both of those Taco Flow-Checks in the down position? Sometimes, someone will raise the weighted check via the knurled dial and leave it in the up position which will allow gravity flow.

There might also be some debris in the Flow-Checks to prevent the weighted check from closing all the way.

You might also be getting flow up through the return, through the pumps.

Both of the screws are turned down. One of them was unscrewed by a few mm before, but screwing it all the way down had no impact.

Is there a way to inspect it? Id imagine not without draining the system.

What does that last sentence mean? Do you mean water is flowing backwards from the circulation pumps? How could I check for that?

Alan (California Radiant) Forbes

Is there a way to inspect it? Id imagine not without draining the system.

Correct.

Do you mean water is flowing backwards from the circulation pumps? How could I check for that?

You could try feeling the vertical pipes dropping to the two pumps with no zones calling for heat. If there's gravity flow from one zone and not the other, the one with gravity flow will be hotter.

And you can do the same on the pipes leaving the flow checks.

EBEBRATT-Ed

Flow checks can stick. Maybe this will help see the attached. You might be able to unstick/clean them.

If not it looks like the copper coming off the main is a lot smaller. You could lock the old flow checks open and install a copper "sweat flo check" in the copper line.

SDAV

Alan (California Radiant) Forbes said:

Is there a way to inspect it? Id imagine not without draining the system.

Correct.

Do you mean water is flowing backwards from the circulation pumps? How could I check for that?

You could try feeling the vertical pipes dropping to the two pumps with no zones calling for heat. If there's gravity flow from one zone and not the other, the one with gravity flow will be hotter.

And you can do the same on the pipes leaving the flow checks.

I turned my boiler on earlier when the inside temperature dropped to 68. I set the thermostat to 69, just until I could hear it call for water. 3 hours later the house is maintaining at 72*. Both return lines above the circulator pumps are about the same temperature, one is slightly warmer. The supply lines are both very different temperatures. The one to my 1st floor is still incredibly hot. This sounds like a flow check valve issue from what I'm seeing. Is there anything else I should check before I settle on that?

All of my radiators turned on appropriately earlier, but it definitely seems like one of them in particular stays warmer than the rest when it's not calling for heat. Maybe it's just because it's the biggest one?

I'm really new to all this, but I assume this situation will cause my boiler to run more than it should and use more oil. Is that correct? Aside from that the main inconvenience is that although the registering temperature is higher, it doesn't feel as comfortable as when the heat is working properly.

SDAV

EBEBRATT-Ed said:

Flow checks can stick. Maybe this will help see the attached. You might be able to unstick/clean them.

If not it looks like the copper coming off the main is a lot smaller. You could lock the old flow checks open and install a copper "sweat flo check" in the copper line.

Thanks for the input, I'll look into the sweat flo check product.

Is it worth trying to exercise the valve to see if it will reseat properly? Off hand it doesn't seem like it would do much, but I haven't worked with one before.

EBEBRATT-Ed

@SDAV

Yes you can try exercising it. The clue that will tell you is if a zone is hot and stays hot (overheating that zone) and the circ pump for that zone is off that is a flo chek issue