Boiler reaching 200 and holding. IS that normal?


Old 12-06-17, 01:47 AM
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Boiler reaching 200 and holding. IS that normal?

Please bear with me I will try and explain the best I can. The system is Hot water baseboard.
My (very old) folks had a very nice Weil Mclain boiler installed a year or so ago. With an 80 gallon indirect. I was over their house recently and it was a mild day approx. 60 I heard the boiler going pretty steady and decided to inspect it (since he had a new air purge installed). Well I checked the aquastat temp and it was holding at 200. Not the boiler Gauge ( I think that may have been reaching 190+ give or take! I wasn't really focusing on that. And the pressure was (not sure) perhaps 25-40 psi.
The Digital reading I was observing was the digital Aquastat. It was holding at 200. I did not see, in its loop sequence any low limit. So I am guessing they may have just a high limit.
Please help me if there is any concern that this may be a bit high especially in the summer?
PS the reason I am familiar with high/low limit. I had one put in a few years ago and the installer kindly showed me how to lower the high low for the summer versus winter. However I only go up to 160-180 in the winter and lower it 120-
140 in the summer.
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Old 12-06-17, 07:41 AM
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Is this a warm-start or cold start boiler? Lower the setpoint on the aquastat. Since the installation is only a year old, call the installer back.
Old 12-06-17, 10:05 AM
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What you have is a cold start boiler with only a high limit. You do not need a low limit because you have an indirect hot water heater.

200 deg., although maybe a little high is not dangerous and can be lowered manually.

The ratings of the indirect heater for GPH output is figured with 180 deg. boiler water going through the heating coil in the tank.

I would lower the high limit to 180 to start and if you still get enough hot water you can go lower and experiment until you reach a point that will use the least fuel but still give you adequate hot water.

An 80 gal tank is a good size tank for residential, where a 40 gal is more normal. Maybe the installer, because of the size of the tank coupled with the heat demand in the winter though it might not keep up with the hot water demand.

200* is definitely high in the summer months and I would lower to 180* and try for the winter but it all comes down to your hot water demand.

An 80 gal tank is generally just put in on request and they must be using more than the normal amount of hot water.

One more thought. Your tank, weather it be through the tank control or the aquastat has a priority setting which means in the winter time if the stat and tank call at the same time the tank will have preference before the heat.

A little long but I hope this helps a little.

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