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Author:
Don411 (IN)
From what I can tell she's 50-60 years old.
We are converting the old house from oil to natural gas, and installing a new Bosch Greenstar FS=151 condensing boiler.
This unit is a combi unit that makes DHW at 4GPM, and it's direct vent so that we can eliminate the chimney in the house. Permits are being pulled, the gas company has to tap the main and bring gas into the house, so October is the target install right now.
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Author:
Paul48 (CT)
It's an absolute must, that a heat loss calculation must be done for the home. If the old boiler heated the home, then that Bosch combi is massively over-sized, and you will never see higher than mid-80's for efficiency. In that case, you might as well put in a 3-pass boiler, with an indirect. If your contractor didn't do a heat loss calculation, he doesn't understand condensing boiler technology. I don't mean to be harsh, but I'm concerned that you get your money's worth.
Please remove your contractors name from your post, he can't defend himself.
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Author:
Don411 (IN)
OK contractor's name removed. If the current boiler is 126,000BTU and the new one has a heating capacity of 135,000 btu, how is it massively oversized? I didn't ask the contractor specifically what calcs he did, but he had his calculator out for something, and I know this guy has a good reputation specifically with regard to Bosch condensing boiler installations with good references.
We just bought the house, so we haven't been here thru a winter yet...I know there is no insulation in the walls though
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Author:
bernabeu (SC)
You need to decide BEFORE new boiler installation whether you will, or will not, upgrade your insulation.
The boiler should be sized to the actual load.
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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Author:
Paul48 (CT)
The old boiler is probably running slightly under 70% efficiency. Which translates to much less heat output than the 126 input, and it is probably over-sized. The only time you get to over 90% efficiency is when the boiler is condensing. The problem with combi boiler is, they rarely match the heat load, and that is critical with a condensing boiler. Please...Take this situation HeatingHelp.com. I am a DIYer with mechanical skills. heating is an interest and hobby of sorts. Let the pros at HeatingHelp explain this to you.
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