Question on radiant heating leak inspection and possible solution

wykrrr

Hi,

Currently I have a radiant heat system as following:

I have a closed system, and I've noticed that the pressure slowly decreases when the system is running. Since I'm using a tankless water heater, I know it loses water through condensation over time. My assumption is that this gradual loss is contributing to the pressure drop.

However, I'm still trying to determine if there's a leak elsewhere in the system beyond the condensation. I don't have a bypass for the water heater, so my plan is to turn the water heater off, use a bucket of water, and run a sump pump to push water into the purge valve and out through the drain valve. I have a couple of questions:

1. Does the tankless water heater allow water to flow through when it is turned off?
2. How long should I run the sump pump to ensure there are no leaks?

If there are other places leaking, I am going to try the leak sealer to see it helps. If no other places is leaking, my plan is to turn on the "city water" valve to always feed in fresh water around 18psi pressure.

Thanks

hot_rod

that tankless should not lose pressure ever. Does the pressure drop to zero psi?

I would sudpect a pin hole in the tube perhsps. Isolate the tube from the piping, put a 60 psi, or whatever water pressure you have, water test on it, that will tell you quickly

ScottSecor

I agree with Bob. Tankless, boiler or combi unit should not lose water - basically a sealed unit. Look for damp areas on the floor or muddy areas outside near the slab. Thermal imaging tool can also help.

STEAM DOCTOR

There condensation is not from the water in the pipes. It's from the moisture in the gas. Totally unconnected. You're almost certainly have a leak somewhere