Residential stm boiler overfilling every hard steaming cycle

jjsabby

good evening. Residential steam radiator heating system working well for the last 15 years is now experiencing an issue of overfilling after every hard steaming cycle in the morning. One pipe parallel flow with dry and wet returns.

Of course the issue is too much water in the boiler after the heating cycle is over, requiring a manual draining of the system. And occasional water hammer near end of cycle.

auto feed valve working as designed, no leak by. I suspect a wet return including near boiler piping plug.

I am interested in the forums feedback and experience, thank you.

Big Ed_4

How much higher is the over feed over the normal level and if you don't drain it out what happens ?

EBEBRATT-Ed

Water is getting into the boiler somehow. Leaking tankless heater coil or indirect water heater if you have those, leaking manual fill valve or leaking water feeder.

jjsabby

a gallon or so, again, only after a cold night and long steam (it’s on timer so it is off for several hours during the night).
Eventually it goes out of sight high and I believe that is when I get water hammer. As the weather gets milder, shorter steaming cycles, don’t experience this problem. I don’t think the radiators at the extreme end of the run see the steam and therefore, and the condensate in this case is lost temporarily .

The only external source of water to the boiler is the feed valve, and it is functioning properly.

Could it be that during long cycles, all the remote radiators eventually get the steam and the condensate in the most remote radiators, wet returns, is too slow to return (after the feed valve takes corrective actions)?

Jamie Hall

You may well have a problem with slow returns. That's not your only problem. In the post just above, you mention that the radiators at the extreme end of the run don't see steam on short cycles. While that won't account for your condensate problem — if they don't see steam, they also don't produce any condensate — it means that your system is not adequately vented. And perhaps that the mains aren't vented at all.

This needs to be addressed before that slow return problem can be considered — although there may also be a serious problem with pipe pitch as well.

LRCCBJ

Consider the fact that the auto feed valve typically has no delay. When the level in the boiler reaches the probe, the probe calls for the feeder. But, you don't want to feed as the water is up in the system at this point.

Consider a delay timer that prevents the feeder from running for 10 minutes.

You didn't mention which boiler you have and where the probe is on that boiler. Some of the ECR boilers have the probe four inches above the bottom of the sight glass because ECR is deathly afraid you will run out of water.

The delay timer works perfectly with these systems and works with the traditional McM feeder that is also set to provide water well above the bottom of the sight glass in most installations.