wiring hydronic radiant heat relay to boiler aqua-stat

[ritelec]

Hello.
I helped a friend over the phone to trouble shoot his hydronic radiant heat which wasn't getting hot. He was emailing me photos and I talked him through it.
He has a boiler with 8 honeywell zone valves for base board heat. Off the boiler he has a separate zone valve with a separate circulator pump and a Honeywell RA832A dpst relay for the radiant heat with a mixing valve.
My question, in the RA832A there is a T T which goes to the areas thermostat. There is also an X X which is an auxiliary contact which I'm gathering goes back to the T T on the boilers Aqua-stat ( I didn't ask him for pictures of the inside of the Aqau-stat)

If any of the 8 baseboard zones are energized, the end switch makes, the boilers circulator pump comes on and the boiler will heat up if needed.
If the radiant heat zone is energized the radiant heat circulator comes on and the X X terminals send power back to the aqua-stat T T terminals (I'm gathering) to control the boiler.

What about the circulator pump on the boiler?? Besides the boiler being energized so will the boilers circulator pump even though there's no boiler baseboard zones open.
Is this correct?

 

[ritelec]

edit, the T T from the RA832A acually goes to the radiant heat zone valves end switch, not the thermostat. (sorry)

 

[ritelec]

Not seeing the inside of the aqua-stat, I'm wondering if there is a burner termination and not just the T T and circulator terminations. Stand down, I'll ask for a picture tomorrow. Thank you

 

[hbiss]

Doesn't matter. The main circ can run with all zone valves closed.

You are correct in how the system works but I don't know what the designer was thinking for the radiant with the extra zone valve and circulator, but that's a plumbing problem.

I would think that if it's operating properly electrically I would check the zone valve as they are prone to failure. Probably stuck closed.

-Hal

 

[jim dungar]

My house was set up with the radiant heating circ pump on its own heating loop without control of the boiler.
The baseboard heat ran much more often than the radiant zone (better insulation in the new construction) so there was always enough residual heat in the water. This way we did not have to interface with the boiler control at all.

 

[kwired]

My house was set up with the radiant heating circ pump on its own heating loop without control of the boiler.
The baseboard heat ran much more often than the radiant zone (better insulation in the new construction) so there was always enough residual heat in the water. This way we did not have to interface with the boiler control at all.

Radiant loops will have call for heat for long periods of time, then will have long periods with no call as a general rule. If space were warmed up then you had a system failure you often can get by for longer before the space is significantly cooled down. You might have that radiant loop calling for heat all day long but if boiler cycles with the baseboards there may not be all that much boiler down time, the recovery time was going to be long anyway and occupants may not really notice anything out of ordinary.