Indirect Hot Water Not getting hot!!!

Mike Z.

I just installed an indirect hot water heater. I have a 3 circulator zone relay with zone 1 priorizitation. I connected the hot water tank to zone 1 in the relay and zones 2 & 3 to 2 & 3 in the box. then i wired the relay to the aquastat and the 3 circulators to their appropriate zones 120v output in relay. Every thing functions like it should, but the boiler water return coming from the IFHT is cold, but it is calling for heat. the circulator is running but not pushing water through the coil in the tank. I think it is air bound because there was 1 time where zone 1 got up to temperature and i had a tank full of hot water. I showered and went back to basement to check on things when i realized zone 1 was calling for heat again(because of the shower) but the return from the HWT is cold. its been like this for an hour now and circulaor is getting hot... what do i do now, how can i bleed the tank? what is happening???

c.t.kay

put a church key bleeder on top of the highest loop of pipe coming in and out of the indirect boiler supply and return piping,bleed out the air ,close the valves and enjoy the water.

LIBOB

Purge Set-up

Can you isolate that tank so you just purge that only? Theres alot of resistance in that indirect coil. Try the fast fill on the feeder to get a little more pressure in the system to push that air out.

Mike Z.

Fast fill

If i do a fast fill and increase the pressure, how do i get that pressure back out of the system so that it is about 12lbs cold?

LIBOB

The fast fill

will boost the pressure to get the zones purged out. Keep purging the zone then turn off the fast fill. The pressure will drop then close the boiler drain

Weezbo

the supply and return may be fighting each other as well...

not saying that it isnt air locked buh why would it be? when it was installed you filled the supply water and then the boiler water....after purging the tank of air on the potable supply side you purged the air out of the tank filling it , then opened the valve back to the boiler return header....so, unless you have a problem check valve,or closed valve of some sort you should get flow.... if it is piped wierd it might be fighting another pump, or the impeller was melted because the juice was shot to it when dry or maybe just maybe the impellers bound on some solder and the pump cartridge needs to be removed and the pump flushed of whatevers binding it. or, if it has a zone valve in the equasion it too may be stuck closed and thepump is dead heading because of that....or maybe the pump is headed out of the tank, or its on the down stream of all radiant and its simply drawing low return temps back to the indirect... these are my best guesses at this momment... TRY THIS....turn the pump off and jazz up the other zones....heat circulating thru the indirect ? backwards?

Einsiedler_2

flow

hot supply, cold return = no flow.
pump size?
pipe size?
rated pressure drop across the coil?
a piping sketch might help as well.


EIN