I have a hot water heating (installed in 1991) with a tankless hot water system. We had leaking from the boiler and a plumber put in a new autofeed/fast fill/pressure valve done in November of 2008. It corrected the leaking problem from the pressure relief valve pipe. (about a quart a day). He made sure all air pockets were removed. In the past several weeks, we notice that we have been losing hot water in the middle of the shower. It does not get freezing cold, and you can finish showering. It takes anywhere from 6 minutes to warm up again (sometimes I wait so long that I just finish up and get out). Recently, we have noticed sloshing sounds coming from the pipes in the morning when the heater kicks in and it sounds like you are at the sea. Any suggestions on how to fix the problem would be appreciated.

Wayne

For some reason it sounds like you have air back in the lines. Bleed the system and see if that helps. For any more info please post the exact brand and model of unit and since you have a combo style unit you will need to post pictures since they can be piped in many different ways.

Thanks a lot for your response, HVAC1000!

Is it difficult to bleed the lines? Should I be calling the plumber back? Am a little afraid of messing the boiler up in the middle of winter with a snow storm predicted for tonight. Or is bleeding the line as simple as hooking up a hose to the drain valve, opening it up and letting the water drain out for awhile? (Do you need to turn the boiler off?) Also do you think the two problems are related - sloshing sounds and losing the hot water in the middle of showers?

The boiler we have is a Weil McLain cast iron water boiler #A-568WT Complete with Carlin Z-1 flame retention oil burner, two circulators with isolation flanges, R-845A relay, 8 gallon tankless coil, L-8124A aquastat, two flow valves, feeder, #3000 extrol tank (all copied from the original contract when we purchased the boiler in 1991) We have 2 heating zones in the home. Picture of set-up attached.

Thanks again!

It sounds to me like the tankless coil might be partially clogged up or the coil coated with water stone or whatever you have in your neck of the woods that would cause scale on the inside of the coil. This is just a guess on my part. Since you are not familiar with these units I recommend you call in a professional who knows these systems and get it fixed. Most if not all work on these kinds of systems are beyond the average homeowner.

The reason I mention coil clog is the fact that you are running out of hot water and or it is cooling off near the end of the shower. This is a symptom of exactly what I mentioned above. Sometimes the domestic hot water coil need to be cleaned out with a mild acid circulation when the coil is disconnected from the unit and that is one reason it is not good for the homeowner to mess with it.

Thanks again. Guess will have to bite the bullet and call in the plumber. The last time when we had the leak (in November 2008) he said it could be due to 3 things: the expansion valve is not working right, the tankless hot water heater need to be REPLACED and I forgot what the third one was. The least expensive was to try replacing the expansion valve first which was what he did. So I imagine he might be agreeing with your assessment being a problem with the tankless water heater although he didn't mention about being able to clean out the coils vs. buying a new one! :(

So I imagine he might be agreeing with your assessment being a problem with the tankless water heater although he didn't mention about being able to clean out the coils vs. buying a new one! :(

If they are copper they can usually be cleaned but with today's labor rate it might be cheaper to replace.