Radiant Heat Install Problems
Hello All
All input and suggestions are appreciated. Dealing with a sort of head scratcher.
We took out an existing gas fired cast iron boiler that was doing 3 radiant zones and one first floor radiator zone and installed a Weil-McLain ECOTEC with a buffer tank. We removed the radiators on the 1st floor at the customers request and installed Rehau heat transfer panels under the subfloor with a new 5 port manifold. It came out to 5 loops with 1/2” tubing - all loops under 250ft with no joints. We also replaced the (3) existing radiant manifold with new like-for-like manifolds.
Upon purging and starting the boiler, the new first floor loop heated beautifully. All plates got warm and water was mixing well through the Caleffi mixing valves. However, when turning on the other zones, it seemed as if all of the mixing valves suddenly closed. I was unable to get hot water to move through the mixing valves. The pump body’s were all screaming hot. I got on the phone with Caleffi tech support and really got no where. He suggested I might’ve used the incorrect valve for the application despite the tech documents stating that they were suitable for hydronic heating. Anyways, today I removed the Caleffi mixing valves and replaced them with Taco mixing valves and still got the same result. The new first floor loop was heating, however all of the existing radiant will not heat and the water is not flowing through the mixing valve. Red hot up the hot side of the valve, ice cold on the other side, pump is running There is no air in the system as I relentlessly purged each manifold several times.
I’ve attached a picture of the near boiler piping and basic drawing on flat paper of what it looks like. Let me know if you guys see anything or have any suggestions on what to check. Thanks!!
Disclaimer boiler install was not finished when these pictures were taken.
Comments
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Are those Taco circulators oriented to pump down or to pump up?
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Pumping up. Arrow on back of volute is pointing up.
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The piping work looks amazing.
The only thing that pops in my head is the IFC or checks valves on the circs or mixing valves was installed backwards. It's happened to the best of us (not me of course, lol).
Can you post pics of the completed work, in and out of buffer tank, etc?
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Yes, will post more pics tomorrow when I get back on site.
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Why are there mixing valves at all? Condensing boilers can run at whatever temp the system needs. With that said, you're most likely looking at an airlock rather than a mixing valve issue.
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Aren't you missing the return from the system on the mixers? Unless it is hidden behind something?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
In the photo, its just hidden behind the cast iron header
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I see it in the other pic, now.
A purge on the return from the radiant manifold can speed up the start up. Purge every loop right back to the boiler header. A boiler drain right above the white handled ball valves.
Are all the manifold actuator valves, white knobs open? All the flow setters opened?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
2
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