Heating coil

[Stevo120]

This is an interesting set up!! The apartment heater is fed from the water heater with recirculating domestic hot water. Basically a heating coil you would see on any hot water heating system. I'm having issues getting hot water through the coil. It's coming in hot and cools off about 20 degrees on the leaving side of the coil with the fan off. I have bled the system a bit and seem to have good pressure on the leaving side but I know it could be pressurized from return side. Ofcourse the valves are frozen and unable to shut off. Any ideas on how to make my customer happy?!?!

[stickinit2thman]

This is an interesting set up!! The apartment heater is fed from the water heater with recirculating domestic hot water. Basically a heating coil you would see on any hot water heating system. I'm having issues getting hot water through the coil. It's coming in hot and cools off about 20 degrees on the leaving side of the coil with the fan off. I have bled the system a bit and seem to have good pressure on the leaving side but I know it could be pressurized from return side. Ofcourse the valves are frozen and unable to shut off. Any ideas on how to make my customer happy?!?!

Ive dealt with those.Also it should have a pump,problably inside the air handler.Make shure its working and pumping good.Its a direct drive pump and thats the only moving part to the system.What kind of valves does it have?If they are gate valves,if so verify they are open completly.On gate valves the gate can break loose from the shaft and fall closed or even partially closed.You may need to open the system to make shure you have no excessive pressure drop accross valves after you verify the pump is running.They are really effective and relaively cheap to operate.The only moving parts are the pump and the blower.Really simple and effective

[smoke]

Sounds like you only have 2 areas to troubleshoot, hand valves and circulating pump. If it's recirculating the domestic hot water from the water heater tank then you won't have higher return pressure to worry about. It will be equal pressure.

I would bet money that there's something wrong with the circulating pump, either control side, motor or impeller.
You should also offer to replace those seized hand valves.

~smoke~

[stickinit2thman]

Echo in here

[Stevo120]

Thanks for the reply guys!! The info is useful!! But to reply to you, I know the pump is working, how well who knows!! But I am getting hot water to about half of the coil. So without having to cut supply and return pipe to blow out the system is my best bet to shut off return and try to blast the coil. I'm afraid the scale may be really built up. So with that in mind any ideas on how to safely treat the coil for scale build up on the domestic hot water side. Remember it's drinking water along with heating.

[thermojohn]

Is this a First Co unit? The check valve may be stuck. The coil discharge, if TEE'd into the tank drain, may be plugged with sediment at the bottom, not allowing flow. You really need operable shut-off valves.

[Stevo120]

Thank you! I will check all those things!!

[genduct]

You should check the system design, because if the hot water coil circuit is allowed to stagnate, then you could be growing bugs when space heat not calling. that run should be cut off and drained IMO And I think there is a code thing about that, need to look