Hoo boy!We have a boiler at work to produce hot water for a one bay carwash,and it also runs the floor heat.
Up until last Dec we had 2 separate systems( hot water heaters) to do this. They became defective due to age.
We had a guy come in and told us a boiler will do both jobs at once with the help of a heat exchanger.
After they hooked it up when the boiler shut off it would pop and bang rather loudly(like it was gonna blow up)
We called them back and the service guy says we need an expansion tank( which the guys doing the install said we didn't,they had it with them)
expansion tank was installed and worked good for awhile
Mid summer the popping and banging started up again. The service guy said there was calcium build-up in heat exchanger and circlation pump
Again it worked fine for awhile
He came back again last week and said we need a new pump and heat exchanger as it is probably full of calcium
Today we got brave and took the pump apart to see if it was calcium.(he has not come back yet to install new stuff)
No calcium, but a lot of pressure in the expansion tank(obviously)
We are wondering if the expansion tank is in the wrong spot ie. working against the re-circulating pump? It is teed in after the pump and just before the heat exchanger.We feel the water in the exchanger can not release because the constant flow going to the exchanger is working against it
They deny that it is a problem and blame it on a lack of a softner.
Interesting enough, after we released the pressure today, it is working fine for now again.(probably until the expansion tank fills up and the water in it has no place to go)
Sorry for the lenghty dialoge, but it gives you a bit of history to go on
I am gonna take some pictures of the set-up as well