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Topic # 216605 4-Jul-2017 18:35
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My wetback started leaking badly yesterday and plumber says that as the woodburner is old he doubts I can get a replacement. He suggests plugging it off and only using electricity to heat the water. My question is will it cause any damage to the cylinder etc if I turn off the water at the mains to ease the leak so I can have a fire tonight? I would hate to do more damage. Any help will be much appreciated.


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  Reply # 1812800 4-Jul-2017 18:43
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What happens normally if your water supply gets cut? eg during maintenance. Is there something in your instructions for your wood burner? I would speak to the plumber and ask them the question.


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  Reply # 1812801 4-Jul-2017 18:43
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Your plumber doubts incorrectly. I have an old Metro Fires with wetback ability but, although the plumbing is there, it's not hooked up. I've been looking at replacing it in a few years and getting the wetback hooked up. I haven't looked at any other manufacturers and given the amazing service I've had from Metro over the past two years while I've been fixing up my fireplace, I don't think I'll bother. There's a Metro Fires page about their wetbacks here. An internet search on other manufacturers will likely turn up similar.

 

Edit: I've probably read your post wrong. I'm now thinking the replacement of which you speak would be for your wetback attachment, as opposed to an entirely new woodburner. The best think to do for a wetback attachment replacement would be to get in touch with the manufacturer. If it's old it may not appear in any catalogues anymore and retailers tend to be more inclined to sell you a new appliance rather than help you fix your old one.


 
 
 
 


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  Reply # 1812805 4-Jul-2017 18:45
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Imo probably not. Unless you run out of water to heat.

Wait for some more replies.

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  Reply # 1812815 4-Jul-2017 19:17
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You need to contact another plumber. DIY "blocking off" a wetback then lighting the fire could result in a spectacular explosion.
Even if running the wetback "dry" safely, you could destroy it when fixing the leak might be a simple job for a plumber.

Edit:
I'm assuming that the plumber hasn't seen it?



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  Reply # 1812817 4-Jul-2017 19:22
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I have an old Kent, which has always been serviced but as it was installed in 1993 I can't f ind anything online about it. The Kent NZ website phone number goes to Sky TV!!  The plumber is looking at plugging the pipes that go from the woodburner to the hot water cylinder. The wetback is inside the fireplace somewhere and he feels this is the easiest to do. I doubt I will bother with trying to replace it until I replace the whole fireplace.


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  Reply # 1812824 4-Jul-2017 19:26
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First up - if you're going to plug things, ensure that at least one of the pipes in or out of the fire is left open. Block both of those and light the fire, instant bomb.

Apart from that, lighting the fire without water in the wetback wil more than likely result in the radiator inside the fire getting burnt out. They are generally made of thinner metal than the firebox itself, and rely on the water within to essentially keep the temp down and prevent damage to the pipes. This won''t happen on a one-off, and if it truely is buggered already, won't be an issue for you unless you feel it can be repaired.

Edit: Fred beat me to it.

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  Reply # 1812831 4-Jul-2017 19:35
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jancor: I have an old Kent, which has always been serviced but as it was installed in 1993 I can't f ind anything online about it. The Kent NZ website phone number goes to Sky TV!!  The plumber is looking at plugging the pipes that go from the woodburner to the hot water cylinder. The wetback is inside the fireplace somewhere and he feels this is the easiest to do. I doubt I will bother with trying to replace it until I replace the whole fireplace.


Okay got that.
I think for tonight, if you shut off the water and the wetback is leaking a lot, then switch the power off to the cylinder. Otherwise the element may run dry and burn out.

Where is @ardwood ?



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  Reply # 1812832 4-Jul-2017 19:36
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As it is 24 years old I doubt it can be repaired. At the back of the woodburner is 2 pipes - one goes up the wall to the roof and the other below the floor. It is these the plumber is going to block off. Decided to leave water on now as would hate to damage the firebox or something else. Are the wetbacks easy to remove? Just wondering if he should remove it altogether. 




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  Reply # 1812834 4-Jul-2017 19:39
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I have the hot water cylinder switched off so no power heating it. NO point in doing that if it has to be drained when the plumber comes.


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  Reply # 1812965 4-Jul-2017 22:46
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I don't know about availability. But I do know if you can get the old part out an engineer will make a new one for you. It's not cheap but it's an option. I'd guess at 1/3 the price of a replacement wood fire, but you never know.

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  Reply # 1812997 5-Jul-2017 02:31
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Depending on how the wetback is designed - if it is the type that are just bits of copper pipe brazed together. Any decent plumber should be able to repair it. But can it be removed from the firebox without the firebox falling apart? And if the reason it is leaking turns out to be damage from aggressive water, then the copper will probably be too thin to reliably repair.

 

If the plumber is only talking about capping off the pipes that come from the cylinder, and leaving the pipe connections from the wetback open. Then that is OK (as any pressure in the wetback itself can easily vent). But you also need to disconnect directly at the back of the fire, not at the cylinder end. Otherwise the water will evaporate out of the wetback, as well as completely stuffing the wetback, it also risks burning down the house. As the wetback pipes will get extremely hot, and there is the risk that enough heat can travel through the pipes to start a fire where the pipes go into the wall.

 

There should be a non return valve on the pipework to the hot water cylinder inlet. So if you turn the water off, the cylinder can't drain by itself. But this also means that the leak from the wetback won't stop just by turning off the water to the house. (until the whole cylinder of water leaks out through that leak). Assuming that valve works properly, you can also safely run the wetback fire with the water turned off to the house. But be careful as some houses have equal low pressure supplies to certain taps (most likely shower cold supply). So if some taps keep on working when the water is turned off. You are probably draining your hot water cylinder.






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  Reply # 1813037 5-Jul-2017 08:41
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jancor:

 

I have an old Kent, which has always been serviced but as it was installed in 1993 I can't f ind anything online about it. The Kent NZ website phone number goes to Sky TV!!  The plumber is looking at plugging the pipes that go from the woodburner to the hot water cylinder. The wetback is inside the fireplace somewhere and he feels this is the easiest to do. I doubt I will bother with trying to replace it until I replace the whole fireplace.

 

 

I've recently repaired two of our early Kent fire wetbacks (one '86, one '90 model).

 

Both were 'side' wetbacks. The heat exchanger - made of copper tube - was brazed to threaded brass pipe where it exited the back of the  firebox, held in position by threaded brass flanges.

 

Remove those, the wetback can be lifted out of the fire's front door. I pressure tested them with compressed air in a bucket of water, brazed the leaks & reinstalled.

 

Biggest problem was one of the crox nuts on the hot (upper) side feed to the tank was brittle & split - likely 30 years of hot/cold cycling - requiring a trip to town for a replacement.
The heat exchangers didn't look too eroded internally. I reckon they'll do another 30 years. We use ours every year and wouldn't do without them.

 

Kent is still around. Google them, they'll cheerfully ID your fire for you, and have some parts even for early models.

 

I get spares from trademe as factory prices are ex-pen-sive...


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  Reply # 1813071 5-Jul-2017 09:46
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Do you have a photo of the wetback unit and how it is installed?


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  Reply # 1813091 5-Jul-2017 10:17
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Years ago when I had a fire it was possible to buy generic wetback kits for the flue.





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  Reply # 1813092 5-Jul-2017 10:19
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These guys here made up our last wetback for our old fire .  http://www.superiorheating.co.nz/wetbacks.php    

 

 


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