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Author Topic: Wet Back Questions  (Read 7711 times)

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Offline raskas

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Wet Back Questions
« on: February 10, 2009, 05:46:21 AM »
Hello
Im trying to figure out if i can resurrect my wetback system in my home. Ive got a Rheem 18T.180.15 HWC that was manufactured in 2000 and a Kent firebox set into an existing fireplace,they are about 1.2 mtrs apart.
Now what i need to know is. Can this HWC have a wetback attached ( it has 2 extra inputs about 120 degrees apart at the base) ?. The wet back element has crumbled and has approx 105mm centres for the in/out fittings, i have access to one with 90mm centres, are offest fittings available to make this fit my firebox, or can i modify the box to make it fit ?. Is there anything else i need to consider ?
Thanks for any replys

Cam 

Linkback: http://www.plumbers.co.nz/forum/q-and-a-hot-water-cylinders/44/wet-back-questions/107/

Offline Plumber

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Re: Wet Back Questions
« Reply #1 on: February 11, 2009, 07:21:08 AM »
Hi Cam,

I don't see why you could not resurrect your wetback, there are a few things you will have to take into consideration though. Firstly make sure your Hot Water Cylinder is suitable and find out if your wetback is designed for indirect or direct water heating. To find out if your HWC is suitable for indirect water heating check the HWC manual. If you don't have that then give Rheem a ring and ask them, they are very helpfull. I have attached a picture to show how your HWC would look like if it was suitable for indirect heating (From the outside the indirect cylinder looks identical to the direct cylinder except for the two additional pipe connections on the side of the cylinder. Inside the cylinder a coil heat exchanger is installed, which allows hot water from the wetback to flow into the upper connection and leave at the lower connection to return to the wetback for re-heating. The hot water in the coil indirectly heats the water in the cylinder. having an internal coil no water will come out if you open one of the 2 extra inputs you mentioned, please don't open them though). Using the same method find out if your wetback will suit the type of HWC you have. (Wetbacks designed for indirect water heating usually have provision to bleed the system). I would recommend getting your wetback serviced before you fire it up! Once you have established that the two are compatible, connecting them should not be a problem. Your pressure pipe should be in copper and insulated also the great variety of brass fittings you can get at any plumbing supplier should make it easy to connect the two together. I'm assuming the two extra inputs you mentioned are vertically above eachother. Use the top one as the flow to the wetback and the bottom one as the return from the wetback. Also have a look and see if the wetback has an integrated circulation pump, this is required to circulate the hot water between the two.

I hope this helps to get you started :).

Regards
Please note that the advice I am giving is only my opinion and not necessarily a fact.  Please refer to our terms and conditions.

Offline raskas

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Re: Wet Back Questions
« Reply #2 on: February 13, 2009, 12:01:45 AM »
thanks for the reply
i think my HWC is not suitable for wetback as the two extra inputs are the same height jut 120 degrees apart,

Cam 

Offline Plumber

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Re: Wet Back Questions
« Reply #3 on: February 13, 2009, 02:24:31 AM »
Its my pleasure,  I would still check with Rheem though some cylinders are manufactured differently but can sill be used for indirect applications.

regards

Offline worker

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Re: Wet Back Questions
« Reply #4 on: March 03, 2009, 11:13:30 PM »
The connections on your cylinder are alternative water supply inlets. as you only need one the other two are blanked off. they are not really suitable though usable.your best bet is to raise your cylinder and fit flow and return pipes to underside of cylinder.
 the building code G13 deals with the minimum fall for your flow and return pipe (1:7 between heat exchanger in firebox and your storage cylinder and no less than 1:20 at circ. pipe flattest point).
 The higher your cylinder the higher the circulating pressure. Almost all wetbacks in NZ are direct circulation. 1" pipe is the standard dia. though 3/4" can do.
 Never install if you are not sure before you start.
 Your H.E. can be adapted to suit hole centres or you can redrill firebox and flange H.E. with big washers or plate steel of no less thickness than fire box.
you cylinder MUST be open vented to atmosphere
dont blow youself up a cylinder exploding from trapped steam will destroy you house checkout youtube 'exploding hot water cylinder'

Offline spud

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Re: Wet Back Questions
« Reply #5 on: June 07, 2010, 07:17:31 AM »
You shouldnt be doing this kind of work unless youre a certified plumber....end of story.


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