Tempering value issue ? Have to turn iso valves off

Issue: This morning, my Solo 40 boiler was at 170 degrees, the circulator pump was on, the water between the circulator and first radiator was 85 degrees (heating loop temperature) and the house is 56, when it should be 62 by the thermostat.

My current work around: I shut the valve to the tempering valve off for 5 seconds or so, open it up to full for 5 seconds or so and put it back at the 45 degree position. I then use a valve just after the check valve which comes from the boiler and feeds the 2 circulating pump and turn it off, then turn it back on full.

What happens: The change is not instant but the heating loop temp seems to go up slowly to 90 degrees in the 1st 5 minutes, then faster until it gets to 120 or so within 10 minutes.

I am not sure of the environmental conditions when this happens. I have a programable thermostat where I tell it to be 62 from 10 PM to 4 AM, then to heat up to 68 degrees. Seems like I have done the "trick" 4 times in the last 2 weeks. Last night it was 2 degrees outside. Other times it seems to be 30 degrees during the day when this happens. However, 2 hours to temper the heating loop water is too long, expecially when the "trick" has an "immediate" effect.

My guess: the Termovar valve is "stuck" and the pressue changes impact it just enough. I guess it could be a partially open check valve between the boiler and the circulators, where the pressure changes frees it up and then the Termovar starts to increase the volume of tempered water to boiler.

Any ideas?

How long have you had the Termovar?

There is a cartridge in there that is removable. You could pop it out and see if its gummed up or has something stuck in it that could be causing the issue. Or perhaps it needs a new cartridge? Maybe the ball valve that you put at 45 degrees is wearing and it needs to be turned a little more closed?

Thank you. I will wait for the temp to get higher to see if it is gummed up. I followed your suggestion and closed the valve a bit more, to where I can just hear water moving through it.

The details:

When I went to bed the boiler was 170 degrees, heat loop 130 feeding into the first radiatorr and it was just above 0 and was 66 in the living room.. I woke up at 3:30 and checked the system. It was 170 degree, heat loop was 110 and was -14 and 60 in the livingroom. Still had fuel but filled it up. I came downstairs at 7:15 AM. It was 170 degrees, heat loop was 80 and it was -16 outside and 56 in the living room. I tried my usual tricks but the only temp to change by 9 AM was the outside temp which zooomed up to -5.

Around 10 I turned up the boiler temp so it would be someplace between 180-185. I had a fan going in front of a radiator in the livingroom and I turned that off. And I used your suggestion. When I checked at 11, the boiler was just under 180, the heat loop was 120 and it was 0 outside. I turned the fan back on. Now my house is catching up.

Good idea about that valve. I will play with it some more. I also think I should set the boiler temp up when it gets reallhy cold. A contributing issue could be that the house reaches it's programmed temp, the circulator goes off, the cold quickly cools the radiators (and heating loop) and when the call for heat comes in, the temovar does it's thing. By upping the boiler temp, that should force the same amount of water into the system but at a higher temp, hopefully allowing the heating loop to get hot enough to gain when it is really cold. That is why I turned off the fan, it was contributing to the problem.

I think the key is the valve and perhaps the speed of the boiler circulator? Welll I better get to work. Called in a 1/2 day "to keep the home fires burining".

Appreciate the post and idea. Chris

What temperature sensor is in that mix valve? They usually work around a differential.

I had a 140° sensor in mine, it had a 18° differential, so the return to the boiler needed to reach 158 before it allowed full flow to the system. My valve does have a 100% bypass shut down when it reaches that temperature. I tried a 130°, and ended up going down to a 115° sensor, add the 18 differential to get a return protection of 133°. Check with the manufacturer of the valve and see what the spec is, I think some of the challanges that are posted here, with thermostatic valves, are possibly caused by a too high ° sensor.

I think you may be correct that a cold slug of return from the system is causing that mixer to ramp down supply to the system. You may need to setup a chair next to the boiler with a infrared temperature gun to get a true picture on how the system is performing. My valve can take 15- 20 minutes to respond to a wide temperature swing, hard to catch that without "camping out" next to the boiler

With dry wood the dew point should fall in the 120- 130° range.

Question for you.

If your tempering valve is clamping down on the return to your boiler, is there a flow path so that your zones can keep pumping? If not, something like a hydronic separator would let your zones keep pumping (even with colder water, the radiators would throw some heat) even when the tempering valve is still working on heating up the water.

A diagram of your system would be super helpful if fiddling with the valve doesnt work

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Exactly what I was thinking........... An old electric water heater would be a great buffer and hydraulic seperator tank to pump into from boiler and out of to zones.

TS