Domestic Hot Water Coils

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lzaharis
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Post by lzaharis » Sun. Apr. 24, 2016 4:53 pm

Greeting fellow board members,

I believe the Domestic Hot Water coil is bad-The waterlogged steel expansion tank
was found and drained off, after I shut the fill valve off for the coil and then I opened it and I heard water running and I had to drain the tank off again to get the proper ratio of air to water again and I have left the valve shut off for the Domestic Hot Water Coil Tapping.

With my living on well water and a bladder tank for my water supply I have been spoiled by the balanced hot water flow and volume for both showers and at the taps.

SO what is the normal test air pressure for the domestic coil, 30-45PSI or more?

I have the new Shraeder Valve, 1/2" pipe plug and 1/2" to 1/4" reducer bushing
for the Shraeder valve and I will be checking it tomorrow as the piping to thew coil
needs more work.

The pipe lengths to the coil tapping's were made the same length
and male press fittings were installed in the coil tapping's. GRRRR, HINT, HINT, GRRR.

I will fix this by reusing the sweat bronze union fittings and with steel braided washing machine hose and sweat garden hose fittings for the cold water feed to the coil and the hot water out to the propane hot water heaters tank.

I need to buy another 1/2" plug so I can seal the coil tapping's after checking the coil for pressure, of course if the boiler leaks back through the coil when I remove the piping from the coil I will know its bad without pressure testing it.

Anyway the house is warm and I have been burning a bag a day on average and keeping the dampness out with a warm house when the temps have been in the twenties every night has been good.
Last edited by lzaharis on Mon. Apr. 25, 2016 8:42 am, edited 1 time in total.

 
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SMITTY
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Post by SMITTY » Sun. Apr. 24, 2016 6:37 pm

I would guess the test pressure should be well over 100 psi, since my well cutoff is 70 psi, and nothing's exploded yet. We used to have the tankless coil in the boiler for hot water, but now have an Amtrol Boilermate indirect HW setup.

 
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coaledsweat
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Post by coaledsweat » Sun. Apr. 24, 2016 7:05 pm

100# is good, but make sure it is full of water before you charge it with air.

 
lzaharis
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Post by lzaharis » Sun. Apr. 24, 2016 11:44 pm

SO what you both are saying is barring a hot waterfall when I disconnect the unions;
and install the Schraeder with the reducer bushing and the plug. The 40-50 pounds
of air pressure only will not be an effective test with the "coil" still in the boiler???
I can always borrow a larger air compressor from a relative if needed.

I do not have a DHW coil weldment capping plate to replace the plate and coil assembly.


 
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Rob R.
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Post by Rob R. » Mon. Apr. 25, 2016 5:22 am

Typically a failed coil will cause the pressure relief valve to open. Is that happening on your system?

 
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coaledsweat
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Post by coaledsweat » Mon. Apr. 25, 2016 6:39 am

Cap one end of the coil and charge with 50# to the other side with a gauge and shut off valve. Shut the air off and if the pressure doesn't drop in a day it isn't leaking. You don't want just air (particularly at 100#) in something that you are testing under pressure. If it fails it could be catastrophic. Air will expand rapidly when there is a failure and there could be shrapnel or things flying around. Water can't be compressed, so when it fails you just get wet. Probably not a big deal if the coil is still inside the boiler.

 
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Post by McGiever » Mon. Apr. 25, 2016 7:16 am

If you are going to open the DHW system and sweat fittings anyways, why not do it once and be done...add extra valves and tee fittings for the extra test fittings to remain in place. :idea:

 
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Post by waldo lemieux » Mon. Apr. 25, 2016 7:25 am

Leon,

Before you do anything, what exactly makes you think the coil is bad? Its not clear in your opening post....


 
lzaharis
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Post by lzaharis » Mon. Apr. 25, 2016 8:41 am

Hello Smitty, Coaled Sweat, Rob, and Waldo,

My adding all the detail about what I wanted to do with the "repair" confused things and for that
I apologize.

Rob, The relief valve is not popping off and what you say makes sense though.
The gauge glass was filled all the way up to the upper valve-BUT the water fill valve
was shut off after this.

I am probably wrong simply because the boiler was "hot"-160-170 when I opened the
sight glass gauge valves to check the water level.

I have had no issues with pushing hot water through the heating loop though.
so maybe I am wrong about its having failed "and" the hot water has not smelled
like old boiler water.

All of you have provided sound reasoning to leave the system alone so I will not do anything now.

Thanks much,

Leon

 
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Rob R.
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Post by Rob R. » Mon. Apr. 25, 2016 9:39 am

If the system pressure is remaining stable, I think your coil is fine.

If the expansion tank takes on too much water, perhaps the fill valve is admiting water when it should not...assuming you don't have it shut off during normal operation.

One thing I noticed about your piping is that the fill valve is connected to the bottom of the air eliminator, rather than to a tee in the pipe leading to the expansion tank. I have no idea if that matters, but it is different than the B&G literature. If the expansion tank keeps flooding, it might be worth calling B&G.

 
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Post by CapeCoaler » Mon. May. 09, 2016 9:41 pm

The DHW coil will not pickup boiler water,,,
DHW is at 35+ psi boiler at 12 psi...
what is pressure on boiler...
failed fill valve could cause system to flood...
Our fill valves have always been fitted to the to the return line...

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