Problem With New Boiler

Adam_9

This is a bit of a lenghty question. I live in a 1912 story and a half bung.in Chicago. I just got a new peerless hot water boiler installed. On very cold nights it is unable to keep the temp. steady. I set it for 69 24/7 when I wake it is around 65 and then takes 6-8 hours to get back to 69. My old boiler, which was orig. to the house never had a problem keeping the temp. This problem only occurs at night when the temp. drops very low, like 10 degrees and under. The company that installed it has come back and replaced the thermostat, the "honeywell valve that regulates when the gas line opens", and have just recently modified the boilers damper to stay open all the time, which Im not thrilled about. But sure enough as soon as the temp dropped below zero my house is 63 degrees. I'm starting to wonder if they undersized my boiler in the estimate. Anybody have any other suggestions? Thank You for reading the long message.

MIKE6

boiler size

It does sound like an undersized boiler.I don't see the point in keeping the damper open constantly.This is usually done when they think the damper is not operating properly.If thats the case its in warranty, get a new one.If you have gas heat its possible to have low gas pressure on cold days causing poor heat

steve_29

What's the aquastat high limit set at?

Bump it up to 190

Dave Yates (PAH)

my thoughts too

If the boiler is cycling on & off, then a raise in upper limit will cure the problem. On the other hand, if your boiler's burner is running 24/7, you'll need to check the input to ensure it's operating at its rated capacity and if it is, then it's likely undersized.

Either way, I'd want to check the input to ensure it's running at its rated capacity. If your gas company delivers fuel rated at 1,000 Btu's per cubic foot, then you can time the gas meter's 1' dial (or 1/2' dial for two complete revolutions) and divide 1,600,000 by the number of seconds for one 1' dial revolution. Example: 24 seconds on a 1' dial will equal 150,000 Btu input.

If your gas Btu content differs, use the long version of the formula, which is (3,600 x test dial size)x Btu content of 1-cubic foot divided by the number of seconds for one revolution of the dial size used.

If the input is lower than the rating plate indicates, your installer should be contacted to perform any adjustments. It's possible the gas main pressure might be lower than normal due to the cold weather and the input should be re-checked (following any adjustments) when milder weather returns.

The upper limit can be bumped up to 200 or 210 if needed, but I'd reduce that back to 180 max after the cold snap goes away. Here again, your installer should be making the adjustments if the boiler is still under their warrantee.

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Neil_5

Boiler Water Temp

Can the water temp go up that hight to 210? what is the cutoff point before water turn to steam?

Dale

Where in Chicago

You may want to find out what the street pressure is for your block. Chicago still has alot of low pressure mains "7 in the street and when it's really cold the pressure may drop to 4 inches or less,especially in the morning when all the stats are turned up, this is what happened in Boston last winter and if your house pipeing is too small you may have less than 3.5 inches. You can run your boiler at 220 degrees if you need to, the limit is 250. Don't leave the damper forced open, check the gas pressure at 8 in the morning and turn up the aquastat so the burner doesn't stop too soon.

Dave Yates (PAH)

saturation/boiling temperature

at 12 PSI will be 244 degrees F. I'm assuming the pressure won't be less than 12 PSI and a higher pressure will raise the saturation/boiling point even higher. As a result, setting the high limit for 210 for a brief spell shouldn't create any issues for producing steam. I've seen far too many hydronic baseboard installations where the low bidder utilized 210 F limits to minimize the lineal baseboard footage required in order to shave material costs.

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jalcoplumb_2

What type of radiation...

do you have? What size pump did they install? Does the boiler cycle on and off even when the house is not heating? Is all the air out?

Few thoughts.