Condensate has slow return, causing LWCO to add makeup water, overfilling boiler.

Bodycount

This is my second floor tenants boiler I’ve been sorting out this heating season. I don’t live in the house, so I monitor via a Wi-Fi camera. I physically check in 4-5 days per week. 

Symptoms are; after boiler is running a few hours, the water level drops to the point it calls for makeup water. 

Makeup water is added and then in the morning after they leave for work & boiler is off, water level works it’s way to the top of the sight glass. This takes approximately 2 hours, give or take. 

I’ll stop by to drain and/or skim bringing the water to an acceptable level. 

If I remember correctly, the previous tenant turned off the kitchen radiator. Reading here on HH, has advised me that the condensate might be trapped in that radiator? I also feel there might be a vacuum situation associated with this problem. 

The pics are screen shots from the Wi-Fi camera. 

High water level when cold,

low water level w/ LWCO activated,

water level after auto feed adds,

https://m.imgur.com/a/sZmDeok

ethicalpaul

Can you clarify “ after boiler is running a few hours”? Is it really running for a few hours? Why?

Have you opened the valve on the kitchen radiator? It’s a one pipe system, right?

Bodycount

One pipe system. 

Running equates to call for heat, cycling on / off for few hours and at max operational temp. 

I’m going to have to go into the apt to evaluate the radiator(s). I prefer not to go into tenants space, but this is inevitable. 

ethicalpaul

OK well the reason I ask about your definition of "running" (and yours is a kind of odd one that isn't very useful to my goal--aren't all of our boilers running for hours by that definition?) is because I want to know the precise situation where the water level drops. See if you can find out which, if any, of these might be occurring:

1. The boiler is running (firing) for a long time on a long call for heat from a large setback which may be causing the pressure to go way too high (anything above 2.5 psi), pushing water out of the boiler triggering the LWCO (this high pressure condition should be prevented by a properly set and operating pressure control)

2. The boiler is on a normal call for heat and has poor near-boiler piping that is causing gallons of water to be carried over into the mains, triggering the LWCO. This shouldn't really take hours...it would probably happen any given time on any given call for heat so maybe this one is less likely given your "running for hours" description (is it really only occurring after hours of running?). As I recall from your earlier post this is possible.

3. There is a problem with water returning to the boiler. This would take a long time because the volume of water condensate produced by a running steam boiler is surprisingly small.
3a. The idea that it's getting into a radiator with a restricted supply valve is interesting and could result in a loss of a few gallons if the radiator got completely filled I suppose...it seems like it would be difficult to cause even a small boiler to trigger its LWCO however. It's easily ruled out by making sure the valves are all open. Tell your tenants if they are too hot to put a blanket over the radiator.
3b. A problem that people often propose is a clogged wet return. I think usually when people think it's a clogged return, the problem is actually #2, but there must be some cases where it could really be happening. You'd have to flush the returns to ensure good flow is occurring to rule this out.

Bodycount

Thank you for your very in depth response. 

My Honeywell pressurtrol is set at 0.5 and the differential is at 1. I installed a new liquid filled pressure gauge which shows that it goes up to 4psi. I’m guessing that the water it being carried into the system. 

How accurate are these pressurtrols?

should I try to drop it below the 0.5 setting to try and get the system to run closer to 2psi?

ethicalpaul

4psi is too high, but I don't think it's high enough to make your LWCO trigger.

Pressuretrols are notoriously inaccurate. There is a way to calibrate it involving a very tiny set screw.

I did have another question about your photos that has been bothering me. In the low water level picture, I see a yellow color of an additive like Surge-X, but when it's full I see clear water.

Is this in fact happening? Does the color intensify as the water level goes down? Then go more clear when the water returns? This may indicate that it is condensate not returning like it should (steaming without returning water would tend to increase the ratio of treatment to water)

Bodycount

Yesterday, I replaced the sight glass and added 1/2 container of steam clean additive. 

The mud leg gate valve is leaking (capped at the moment). I’m planning on draining the whole system within the next couple of days to replace said valve with a nipple & 1/4 turn ball valve. 

Draining all the water & additive, replacing with clean water, continue to skim & drain sludge. 

Bodycount

This is what I added. 

delcrossv

I had a very similar situation at one of my MIL's buildings. A combination of two things fixed it.

Make sure all radiator valves are open. I'd pull the vents to make sure the rads drain (boiler off). If the rads only drain with the vent removed, those vents need replacement.

If you have a autofeeder with a delay adjustment, like a VXT, set it for 6-8 minutes rather than fill on call from the LWCO.

You may have pressure problems too, but you'd be shocked how much water can be found in an "off" radiator.

Bodycount

I stopped by at lunchtime to check the pressurtrol. I was never happy with 4+psi.

it was set at 0.5 psi. I was able to lower it one full turn. I was concerned the screw would turn out. 

Let’s see what psi the gauge reads when she fires up. 

I’m also open to changing the setting on the VTX-24 from LWCO to a timed setting. One step at a time. 

neilc

what about the pigtail?
has it been serviced?

Bodycount

Yes. About 2 months ago.