Any maintenance I can do to my boiler? Also a question if I'm missing a check valve...

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KevinPrz

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Hi all,

I have a weil mclain wtgo that was converted to Gas with a Carlin burner. The plumber said it's maintenance free now and no longer needed my yearly cleanings.

I'm just curious if there is any other preventative maintenance I could be doing for my system?

The other question - on my boiler feed should there be a check valve?
 

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Dana

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Boiler "auto feed" valves are already a 1- way valve, but may leak, and check valves are sometimes required by local code. (IIRC in Massachusetts system check valves are required, but cannot be fully blocking, which seems strange- the flapper valve has a hole in it to limit the rate, but not completely block it.) Normal system operating pressures are typically 12-20psi, quite a bit below typical water system pressures- flow is only toward the system unless there is something really wrong. Boiler over-pressure relief valves that come pre-installed on the boiler are typically 30psi versions unless specified otherwise.

Aut0-feed valves causes as many problems as they solve. I usually just turn off the gate valve to block all flow unless I'm air-purging the system. YMMV. In the event of a slow system leak causing a low-pressure condition you'll hear a lot of sizzle & bang from micro-boil on the heat exchangers becoming macro-bubbles forming & collapsing coming out of the boiler long before it's a hazard.

Checking the system pressure both when the system is idle & operating is a good thing to do at least once per heating season.

With a gas burner that was properly adjusted for air/fuel mixture there isn't much maintenance- the mixture doesn't really drift much over time/use, and there should be no soot formation, and with no liquid-spray jets to clog or wear, it's pretty low maintenance. The installer or inspector should have tested the combustion efficiency to verify that it's operating in the right range after adjustments (if any), and left documentation on that. If that's never been done it's probably worth paying somebody to check it (not a DIY job), but that's a once every 5-10 years sort of deal with that type of burner.

With a gas burner the low-limit can now safely go to 130-135F without damaging the boiler, and there IS a modest system-efficiency gain by operating at lower temperatures as long as it's not short-cycling. Testing the minimum burn time when only the smallest (meaning least-radiation) zone is calling for heat may be worthwhile to see if it short-cycles (at whatever temperature you're running), but that's something that only needs to be done while setting up the system controls, not an annual thing.
 

KevinPrz

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Thanks for the reply!

So on my boiler's aquastat, I may benefit by lowering the LO to ~135? It's at 160/180 right now and the diff setting is between 10 and 15. I have never touched those settings.

I'm not sure what is considered short burns but I can time it now that it's so cold here in the Northeast. I know it burns for at least a few minutes when it kicks on.

I have 2 heating zones and a priority zone for the indirect.

What really brought up my question was my relief valve has been opening since the heating started this season - I've been finding a small amount of water in that blue bucket, roughly a gallon over the last week when it's been running heavily... much less before this week.

I know my relief tank is not full of water, but I haven't shut it down to validate the charge is good. The pressure when idle is around 12-15 and I've spot checked it while running and never seen it over 20 psi. The relief valve was replaced as I had a spare(set at 30psi).
 

Dana

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The system pressure is fine.

To get maximal benefit out of the thermal mass in the system, increase the differential to it's maximum setting.

Then it's a matter of testing how low you can set the temp without it dropping below 130F on any part of the burn cycle, and without short-cycling. The high-limit needs to be at least 15-20F above the setting on the indirect though, which may involve incrementally turning down the indirect as the high-limit get's bumped down.

It's worth testing the minimum burn time during a continuous call for heat from your smallest zone (measured by the amount of radiation, not square feet of floor area.) Do do this, temporarily turn the temp down on the indirect and turn the thermostat for the other zone down (or off), then raise the thermostat setting on the "small" zone up by 6-8F, and observe the behavior of the boiler, during that extended call for heat. In a perfect world it would always run at least 10 minutes/burn or longer, but a 5 minute burn time is not an efficiency disaster. Burn times of 3 minutes or less, and 10+ burns/ hour is getting into short-cycling territory deep enough to matter. Maximizing the differential setting will lengthen the burns, as will raising the temperature.

If it's running choppy 1.5-2 minute burns every 5 minutes even at 180F with the differential set to 20F (or whatever it's maximum is), it's worth taking other measures, such as installing a heat-purging economizer (bypassing some of the aquastat controls) to deliver even higher differentials for longer burns, while decreasing standby losses despite higher peak temperatures, lowering the average system temp by purging boiler heat into the zone at both the beginning & end of calls for heat. The simpler versions are a $150-200 piece of hardware, and are DIY-able for those who are comfortable with electrical wiring. They typically deliver ~10-15% fuel savings with boilers on the edge of short-cycling, even more for grossly oversized boilers that always short cycle, but next to nothing with systems that deliver minimum burn times above 5 minutes even on the smallest zone.
 

KevinPrz

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Thanks, I'll test out the timing tonight. My Indirect is set at 115, but the water at the faucet is 135ish - no mixing valve or anything, I think the guys that installed it didn't install the temp sensor right but it seems stable at this odd setting.

I appreciate the advice!
 

KevinPrz

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The pressure relief tank seemed to have lost it's charge... I pump'd it back up to 12psi and will monitor the situation!

Expect another thread in the coming days as I just scored an HW3250 for $62...

Thanks again for the detailed responses!
 

Dana

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It's probably over-done on the pumping, but without peering too closely at the pics I'd hazard its something like

1: Primary loop
2: Indirect tank
3: Zone 1
4: Zone 2

Looking at what appears to be an uninsulated CMU foundation, it's probably worth insulating all of that plumbing to at least R4, since the boiler room is probably the warmest spot in the house, with the highest wall-losses per square foot of above-grade wall. On plumbing where the water temps are going to always be under 150F you can use the cheap closed cell foam stuff used on potable plumbing, but for higher temp stuff you's have to shop by temp ratings. ( The 1/2" wall box-store fiberglass pipe insulation for high temp stuff is under-R and over priced- better to shop online for that stuff.)
 

KevinPrz

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Well the previous owner was a commercial hvac guy but he passed away so I never got a good run down on the system from the architect.

It's 1 indirect tank zone, 1 for 1st FL, 1 for 2nd FL. The 4th is for expansion, maybe finishing off the basement or radiant heat - not sure the original intentions but it's not in use.

I will definitely look into insulating these when I install the HW+3250 next week.
 
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