Home Repair

Boiler too Big?

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A friend of a friend installed a new boiler awhile back. Come to find it, it's too big for my house's system; thus, radiators bang like someone is taking a sledge hammer to them. So much so that my radiator covers actually move away from the wall and radiator! I have to practically shut the heat off nights in order to sleep. Can wake the dead!!

Any suggestions!


I don't think that the capacity of the boiler is causing your pipes to bang. There are a few reasons why your heating system should be the correct capacity for the application, but banging pipes isn't one of them.

Is this a steam system? If so, the pipe banging is likely because the radiators are not pitched properly towards the return so that condensate can run back down to the boiler.

If it is a forced water system, perhaps there is air trapped at the radiators and the air needs to be bled from them; perhaps a zone valve is not opening properly (or is backwards) and the circulating pump is fighting it.

Let me know which system you have and we can discuss further.

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'Too big' generally won't cause the pipes to bang. There must be some other reason. If the system is hot water, you could turn the temp down a bit. If it is steam, Ron hit the nail on the head.
If you have any radiant heat in the system you might need a secondary loop so the water coming back to the boiler is not too cool because the radiant loop is usually hundreds of feet long. Boilers don't like cold water cycling back unless it is a super high efficient system. I would consult a heating specialist to carefully look at, and examine your system and offer a remedy for your particular problem if it persists.


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