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-   -   Weil Mclain boiler question (http://www.diychatroom.com/f17/weil-mclain-boiler-question-167979/)

Marqed97 01-01-2013 10:07 PM

Weil Mclain boiler question
 
I'm by no means any sort of expert on boilers. That said, I'm familiar with how my home system operates, and am comfortable enough to do basic maintenance.

I'm trying to help out a friend of my mom's. He recently bought an older home next to hers, and called me tonight asking about his boiler. I walked through the place 2 weeks ago with him, just to look around. The boiler is a Weil McLain NG fired hot water unit, about the same age as mine (mine is a VHE direct vent, his is *I think* a CG series? With a natural draft. It's much narrower physically than mine. I'll verify all the model info next time I get over there, tomorrow or Thursday.

He had a plumber over to look at it, walk him thru basic knowledge stuff, and the plumber also replaced the Backflow Preventer and Pressure regulator/auto fill valve, bled the system, cleaned the boiler, etc, pronounced it all good. No issues with any of his work. It's a similar piping setup to mine, 2 main trunks with branches off to cast iron radiators.

His question to me was this: the water pressure is correct for a 2 story system, but he says the radiators don't get hot, like my house and my mom's house do (she has a WM 80% boiler and a 3 story house/system). His tridicator never tops 120 degrees F. And I noticed when I was there too that the thing *cycles on and off constantly*. As in pump starts, boiler fires, runs from 2 to 8 minutes, then shuts down. He took the panel off and said that what I think is the 'high limit' is set to 180. The pump is circulating.

Any ideas? I'd like to help him out, he's a long time family friend (and an attorney whose services I may need someday - haha).

Sorry for the long post, once I get going, ain't no stopping me.

Thanks,

Andy

carmon 01-01-2013 10:27 PM

120 not very hot.....

Marqed97 01-01-2013 10:30 PM

Indeed it's not. Mine usually runs around 140-160, more like 160 F today (-10 F here today).

Forgot to add, he just has an old round style thermostat. As does my mom, though the one in his house is quite a bit older.

carmon 01-01-2013 10:35 PM

there should be a controller on the boiler to set water temp..... get it up to at least 160.... 120 is barely a hot fart.....

Marqed97 01-01-2013 10:37 PM

I'll stop by after work tomorrow and take some pictures... Thanks for the reply!

Andy

carmon 01-01-2013 10:41 PM

anytime .....hope we can help.....

Marqed97 01-06-2013 11:42 PM

Finally an update. I went to take a look again. The high limit is set to 180F, pressure is good, it seems to fire up normally, burners look good to
me, pumps running, etc.

So I went and turned his thermostat up to 80F. The boiler cycled on, and continued to run for about a half hour (until I turned it back down) so I'm thinking that rules out the boiler itself. After several hours with the stat set at 63, it started doing the quick-cycle thing again. So I am assuming the stat is shot...it's a few year old Honeywell round style.

I also found out that the system was drained and shut down for 2 winters while the house was in foreclosure, and winters around here can be -20F for weeks at a time. Perhaps the low temps screwed up the thermostat? It looks like a mechanical unit...nothing special about it. The house became occupied again about 2 years ago and the stat was never changed, so...yeah.

He's going to pick up a tstat, any suggestions? It's a NG forced hot water system, old house, not very tight, older WM boiler, 2 wires at the stat.

Andy

carmon 01-06-2013 11:56 PM

try a new stat wont hurt.... there cheap......

how 01-07-2013 01:26 AM

Most Weil Mclains have two temp controllers. A working limit and a secondary safety limit. 160 and 180 are normal settings. 120F would result in rad temps that are too low so hopefully that adjustment will correct the problem.
Sometimes the safety limit is not adjustable but has a button reset.
A picture of the boiler with the cover off will help.

Either the auto temp controls or the tridicator can also be out of calibration.

The manual adjustment of the temp control should turn off the gas when that manual adjustment matches the tridicator temp measurement. This test can indicate if one of them is out of adjustment..


What is shutting down during the call for heat? The gas or the pump?

Marqed97 01-12-2013 12:12 PM

Update:

He bought a new t-stat, a wireless one that can be moved around the house. He must have a very bad draft on the wall where the stat was, because moving it from dining room to living room made a big difference (according to him...I think the new stat made the difference).

Either way, the boiler is cycling much more normally, water temps are up, and he's not panicking anymore.

Thanks for all the advice!

Andy

ben's plumbing 01-12-2013 05:03 PM

if he had an old round honeywell stat ,...could have had a problem with heat anticipater...and as mentioned 120 ..to low ...readjust to 160-180 and continue as you stated....should be fine..ben sr

747 01-13-2013 02:51 AM

I have weil mclain boiler. My high is 180 Usually the water temp gauge says 140-160. I have never seen it say 180 Its fired up now. Just looked the gauge is just below 140 and climbing. Mine is original to house. 1963 still going strong.:thumbup: My plumber told me they don't make them this good any more. Mine is cast iron burners and coils. Zone just closed and it shut down. Didn't get up to 160. My computer is located on the wall on the other side of utility room:laughing:

Marqed97 01-16-2013 09:59 PM

Quote:

Originally Posted by ben's plumbing
if he had an old round honeywell stat ,...could have had a problem with heat anticipater...and as mentioned 120 ..to low ...readjust to 160-180 and continue as you stated....should be fine..ben sr

You hit it right on the head! The itty bitty heating element part of the anticipator wasn't drawing any current at all.

The new round Honeywell stat looks the same but has a circuit board and little DIP switches to set the cycles per hour...been operating normally since I put it in (he returned the wireless unit -- "Too many features! Batteries! I just want a dial!"). Sometimes simple is better.

Thanks for all the ideas and insight, folks.

Andy

REP 01-17-2013 01:57 AM

Well just to be picky,,you mentioned cast iron rads.CI rads are usually sized with 140 degree water temps designs.It will run fine with higher water temps but why heat the water any hotter than it needs to be.It just costs more and it short cycles the burner when its higher.

747 01-17-2013 03:49 AM

Quote:

Originally Posted by REP (Post 1095435)
Well just to be picky,,you mentioned cast iron rads.CI rads are usually sized with 140 degree water temps designs.It will run fine with higher water temps but why heat the water any hotter than it needs to be.It just costs more and it short cycles the burner when its higher.

my high is set at 180 but i have never seen it get this high. It runs around 140-150 I have never seen it above 150. I think circulate is set at a little above 100. When it draws cold water back and the temp falls circulater shut off then fires back up when temp is between 100-110 My water temp usually stays at 140


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