Water flow in heat exchanger issue

Hey guys I have a friend who is having flow issues through the heat exchanger that is in his furnace. He says it’s hot on the supply line and not so much on the return side. I was just wondering if anybody has had that issue and what you did to fix it ? I thought that swapping the supply and return lines to sort of back flow it might help but I have never been in this situation before.

 

Is there an air lock in the system?

Is he transferring that much heat from the exchanger?

What type of OWB is it? Open or closed system?

What type of heat exchanger is it....thinking maybe just a standard water coil?

Is the circulator pump operating correctly?

 

It is an water to air heat exchanger it looks like a radiator in a car
Heat from the exchanger is minimal now but it has worked well for 5 or so years.
It’s an open loop I think it’s a central boiler.
He has a brazed plate exchanger on the system for domestic hot water and it seems to be heating ok so I think the pump is working well. However I don’t know how he has it plumed. Mine is in series so if the pump was bad nothing would get heat I just don’t know about his. I can find out.

 

Find out what brand of OWB it is and contact that company for support or look for troubleshooting info in owners manual?

The following was found on the web.


Air in system Check for air in the water lines or heat exchangers. If you hear a gurgling sound in a heat exchanger, air is present in the system. Shut off the pump, wait 15 seconds and start the pump.


Poor water quality Water with high amounts of solids, sand or dirt can create deposits inside the wall of heat exchanger components, reducing the amount of heat output. If this condition is suspected, contact your Central Boiler dealer.


Deposits in water lines/heat exchanger wails If water high in silica or other mineral content has been used, material deposits may build up on the insides of the supply and return lines and on the heat exchanger walls. If this occurs, the system will need to be drained and then cleaned using Sludge Conditioner (p/n 166). The system must then be refilled with the proper amount of Corrosion Inhibitor Plus™ (p/n 1650) and fresh water.

Return water too cold Water circulation may be too slow. The return water should be no more than 20oF-25°F less than the hot supply water. If the water returning to the outdoor furnace is too cold, it may cause erratic temperature readings. Check for partial air lock or install larger pump.

 

Are there any valves on your main loop you can open to confirm flow rate? If you have a good flow you've ruled out a lot of potential items (air pocket, plugged exchangers, bad pump).

 

My son installed a new pump backwards on his and got similar symptoms. My guess is there was sediment in his return line that got pushed back into the exchanger and blocked off the lower half of it. It would’ve been nice if they’d installed shutoffs and unions upon installation, but it’s all sweated copper. It’s in his garage, so it’s good enough until spring if it doesn’t clean itself out by then. If not, we’ll cut the lines and flush it out with a hose

 

That is what mine was doing when I found this Not getting heat from OWB.

 

Thanks for all the help. I talked to my friend this afternoon and just thought I would let everyone know what happened. On Sunday when I first talked to him I thought it sounded like an air lock. I said I have seen in the past if you bump up the heat some it could break it lose. He went home and turned his boiler up 10 degrees and by morning everything was back to normal. Just thought I would let y’all know.

 

Instead of paying the usual associated fee, just go ahead and but your lifetime membership. You'll probably have more questions at some point, no?

 

That's a good (cheap) trick to remember