Hydronic Zone Startup Question

Vermonster

Hi -

on a remodel job I had to drain the water system so it wouldn't freeze up on me. Now I put it back into service I have one zone that simply won't circulate properly.
I have flushed the loop several times, vented the baseboards, etc ... all the usual stuff. I even completely drained the boiler and started from scratch. I even replaced the circ pump of that zone. When I drain that zone hot water runs through it just fine just from the system pressure. When I go back to the circ pump after 10 min or so it seems there is no water circulating and the pipes get cold.
Any suggestions would be appreciated. Thanks

jmic

Just throwing this out; did you check to see if you have power at the circulator and also at the thermostat for that zone just wondering if something happened with wiring during your remodeling process.
Joe

Vermonster

thanks ... yes I can see the relay trigger from the stat and I feel the pump working

Vermonster

here is a pic of the setup. So far I have:
1. Replaced the pump flanges. The old ones has seized up ball valves in them. I guess originally they would work as flow back preventers?
2. Installed a new circ pump
3. temporarily hooked the pump up to make sue it gets juice.

Still nothings gets past the pump ???????? when I use the drain just above the pump I circulate hot water just on system pressure with no problem. When I shut off the drain and turn on the pump nothing. The return pipes below the pump are cold and the pump sounds like its running dry.

Thanks for any help since now this is of course MY problem. After all I replaced a few windows, so if the heat does work I must have done it, right?
Thanks again ...

Attached Thumbnails

 

TimNJ

What is the direction of your flow? Typically I would have that boiler drain on the return side with a shut off just below it. When you are going to purge the loop shut off the valve so the water doesn't flow past it as you are trying to get the air out.Everything will come out the boiler drain. Then close the boiler drain and open that valve back up and what little air left should be handled by your SpiroVent or air scoop. Is that zone a primary loop or are the radiators in the zone "T'd" off a main loop? Hope this makes some sense. It is easy to show but hard to describe.

Vermonster

thanks for the reply ... I finally did find that the IFC in this pump was stuck and didn't let water through. I switched ou the pump and now everything is fine.

Thanks again ....