Is Overkill gonna hurt…

cko

Have a 1200sqft home with full finished basement, totaling (2400sqft) living space. Wanting to upgrade the 30+ year old gas boiler. Have located a New (LENNOX GWM-200IE) High Efficiency, Gas Modulating Condensing Water Boiler for an Extremely good price…. (Like 90% under retail price). I’ve read that going with to large of a system isn’t a good idea, But considering this upgrade is a 94% efficient modulating boiler I’m hoping it wouldn’t present/create any problems with heating our home with baseboards & our hot water, (3 Zones total),? We’d be replacing a (Hydro Therm Hi-85) which I believe is a 85000 btu boiler from the mid 1980’s. Any advise is appreciated. Thank you,

ChrisJ

cko said:

Have a 1200sqft home with full finished basement, totaling (2400sqft) living space. Wanting to upgrade the 30+ year old gas boiler. Have located a New (LENNOX GWM-200IE) High Efficiency, Gas Modulating Condensing Water Boiler for an Extremely good price…. (Like 90% under retail price). I’ve read that going with to large of a system isn’t a good idea, But considering this upgrade is a 94% efficient modulating boiler I’m hoping it wouldn’t present/create any problems with heating our home with baseboards & our hot water, (3 Zones total),? We’d be replacing a (Hydro Therm Hi-85) which I believe is a 85000 btu boiler from the mid 1980’s. Any advise is appreciated. Thank you,

Buy and install the proper sized boiler after doing a proper heatloss calculation.

GroundUp

That unit only has a 5:1 TDR so the minimum firing rate is still 40,000 BTU. Seeing as you have 3 zones which were all previously served by a <70,000 BTU output boiler, at least one of your zones is going to make it short cycle- quite possibly all 3. Short cycling is the enemy here. Unless you're also adding a buffer tank, I'd strongly suggest getting something else. Even at a cost of 90% under retail, it's likely still more expensive than a properly sized boiler would be.

mattmia2

With a mod con if it can't modulate low enough to match the load it will run very short cycles. There is essentially no mass in the boiler to even out the load. If the current gas supply is inadequate for the larger boiler then you will have to upgrade that to feed the larger boiler.

EBEBRATT-Ed

@cko Just be aware the boiler is only going to be 84 ish% efficiency. Your heating baseboards which require high temp hot water. The boiler can only condense and be 94% efficiency if the return water is below 130 degrees.

And too large a boiler will make this problem worse with a lot of short cycling.

EdTheHeaterMan

I'd say go for it. Saving big bucks on the one time purchase will more that offset all the repairs and long term effects of shore cycling. Besides It ain't my money! and you don't know where to find me after you realize that you have to pay the ongoing costs for years to come.

But I have been known to be sarcastic at times, so maybe not such a good idea.

pecmsg

EdTheHeaterMan said:

I'd say go for it. Saving big bucks on the one time purchase will more that offset all the repairs and long term effects of shore cycling. Besides It ain't my money! and you don't know where to find me after you realize that you have to pay the ongoing costs for years to come. But I have been known to be sarcastic at times, so maybe not such a good idea.

Only because it’s such a Good Deal!

EdTheHeaterMan

pecmsg said:

EdTheHeaterMan said:

I'd say go for it. Saving big bucks on the one time purchase will more that offset all the repairs and long term effects of shore cycling. Besides It ain't my money! and you don't know where to find me after you realize that you have to pay the ongoing costs for years to come.

But I have been known to be sarcastic at times, so maybe not such a good idea.

Only because it’s such a Good Deal!

Will work even better with a couple of Nest thermostats, Don't ya thing?