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3839 posts
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Posted 7 Apr 10 7:37 PM
We have recently purchased a home which has a wetback fire place. The water heats well however there is a tremendous amount of banging in the pipes when the fire is heating up. As the fire gets hotter the banging of pipes diminishes. We hear the water moving through the pipes and then the banging starts, we are really concerned that the pipes will crack or that there is something major wrong.
Are you able to advise us to what the problem may be?
Thank you
Trish
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99 posts
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Posted 7 Apr 10 10:02 PM
Initially the thermo-siphon water flow in the circuit is zero when the fire is first lit, this causes the wetback to boil up pockets of steam until the flow is sufficient to cool the wetback below boiling. Not really good for integrity of the system.
Comes down to the design of the system, longer or too small diameter of pipe or pipe runs not running continuously upward from the wetback to the cylinder could be the cause.
Other than installing some mechanical device to get the water moving initially, then the design issues must be addressed.
Mike
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426 posts
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Posted 8 Apr 10 8:31 AM
A further complication is the possible 'cheap' technique of joining pipes without using swept "T" or swept "elbow" junctions causing tumbulence at the junctions. Talk to a good plumber.
Rex
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3839 posts
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Posted 8 Apr 10 7:31 PM
Our wetback system does the same especially when you've just put the kids to bed at night, so much for peace 'n' quiet!
The plumber (30yrs +) just shruggs his shoulders and tries to ignore the problem, great aye.
System is medium pressure cylinder with wetback loop, only have a small wood burner and doesn't heat cylinder very much, maybe 5-6degs allday. Would put low pressure cylinder and mains pressure coil in next time.
Mike
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1 posts
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Posted 7 May 10 3:54 PM
Trish.
In addition to Mike.
Moste similar problems I have found to have the flow pipe, the top one out of the wetback, to be installed on a fall not on a rise. The flow pipe must rise as Mike says. The higher the cylinder is the better the flow.
Plumbing in N.Z. was the book for plumbing aprenticesand should be in your library, or a similar basic plumbing book would help.
Bloke
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3839 posts
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Posted 7 May 10 11:39 PM
Unfortunately the current generation of younger plumbers dont seem to well educated in the theory, as a result their practical ability in installing wetbacks etc unless under the direct supervision of a mentor who knows the ropes has a lot to be desired. Its hardly rocket science, I feel sometimes they just dont think. Same goes for builders.
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150 posts
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Posted 8 May 10 9:20 PM
Sounds like a poor system to me, for all the reasons stated above. A circulation pump may be your only viable option. Can you get at the pipework or is it all buried in walls etc?
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3839 posts
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Posted 12 May 10 4:42 PM
Trish,
Your system sounds normal to me.
I speak with experience here as we've had a few homes over the last 20+ years.
They all made noises, some more than others.
O I miss a home with one now :(
Bleemin stupid chch fire rules.
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2 posts
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Posted 18 May 12 3:31 PM
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2 posts
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Posted 18 May 12 3:36 PM
I am in the process of installing a new woodburner, As the new fires are higher than the old ones my hot and cold pipes will need to go up aprox 90 mill from where they come out of the wall to the fire. Will this still work. The system works great at present, 25mm pipes
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