Hot Water Coil Installation Advice

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Vampiro
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Post by Vampiro » Wed. Sep. 16, 2015 5:24 pm

Hi all. I will be installing and then plumbing in my hot water coil to the AA-260 (steam setup). Would appreciate any experiences and advice anyone has had.

Here's the parts I'm thinking of.

Copper pipe & fittings, expansion tank, mixing valves & relief valves. Drain valves for the coil. Back flow preventer.

1) I will be plumbing the cold side into the coil.
2) Then will be plumbed to the cold water inlet of the existing gas water heater.
3) Install a back-flow preventer on the cold side to prevent hot water from flowing into the cold water supply.
4) Plumb a bypass, to bypass the water heater in case of a problem, and be able to supply the house with hot water directly from the coil. Install mixing valve on run and also relief valve.
5) Install a mixing valve on the outlet of the hot water heater.
6) Install expansion tank on outlet of water heater piping which will incorporate the bypass piping.

Misc. Install inlet and outlet valves to isolate and drain coil.

Thanks,
Vampiro :devil:

 
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Rob R.
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Post by Rob R. » Wed. Sep. 16, 2015 9:23 pm

Sounds good. Don't forget to pipe a bypass around the coil. You do not want cold water running through the coil when the boiler is not in use, otherwise it will cause condensation and corrosion.

 
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Post by Pacowy » Wed. Sep. 16, 2015 9:34 pm

I would suggest relying directly on the coil w/tempering valve for whatever seasons you run the 260. Unless you are running a large carwash, or there is something funky about AA coils, a 260 has the power to make abundant DHW in real time.

Mike

 
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Vampiro
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Post by Vampiro » Thu. Sep. 17, 2015 1:19 am

Thanks for the replies and advice.

I've included a diagram that I drew up in paint. Let me know what you all think.

Thanks,
Vampiro



For informational purposes only. No warranty or guarantee expressed or implied. Use at your own risk.

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AA hot water coil to HWH1.png
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Pacowy
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Post by Pacowy » Thu. Sep. 17, 2015 10:04 am

I'm not a piping pro so I'll phrase these as questions:

1. If you insist on running coil output into the gas water heater, would it make sense to put the mixing valve "further down the line" so that the heater gets filled with really hot water and basically never has to run?

2. Is it necessary, or even kosher, to put an expansion tank on a DHW line?

3. Is it necessary to put a PRV on the DHW distribution line (i.e., beyond all of the heat sources)?

Hope this helps.

Mike

 
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Post by coaledsweat » Thu. Sep. 17, 2015 6:45 pm

Pacowy wrote:Unless you are running a large carwash, or there is something funky about AA coils, a 260 has the power to make abundant DHW in real time.
I've had the coil out of my AA 260. It looks like a mile of really big copper, no wonder it costs a fortune. They are rated for 12 baths IIRC. :)

 
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Post by Rob R. » Thu. Sep. 17, 2015 8:21 pm

It is pretty common to have an expansion tank on DHW systems, and I think it is required by some codes.

 
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Post by Vampiro » Thu. Sep. 17, 2015 8:48 pm

Pacowy wrote:I'm not a piping pro so I'll phrase these as questions:

1. If you insist on running coil output into the gas water heater, would it make sense to put the mixing valve "further down the line" so that the heater gets filled with really hot water and basically never has to run?

A: If you look, there is a bypass around the mixing valve. This way it can supply the water to the tank.

2. Is it necessary, or even kosher, to put an expansion tank on a DHW line?

A: Yes, thermal expansion takes a toll on piping. This will help lead to longer system life.

3. Is it necessary to put a PRV on the DHW distribution line (i.e., beyond all of the heat sources)?

A: I agree with you. On the flip side It can't hurt. If both fail there is still a backup.

Hope this helps.

Mike
Thanks for the advice Mike.


 
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Post by Pacowy » Thu. Sep. 17, 2015 9:43 pm

You're welcome. On the first one, it seems like if you bypass the first mixing valve you'll need a second one downstream of the tank because the water in the tank could get pretty hot, esp. when you're making steam.

Mike

 
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Post by SMITTY » Fri. Sep. 18, 2015 9:19 am

My only advice would be to NOT buy from Hilkoil ...

Here's my saga from a few moons ago:

My HW Coils Are Looking Rough After Summer in Damp Basement

 
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Vampiro
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Post by Vampiro » Sun. Sep. 20, 2015 11:46 am

Pacowy wrote:You're welcome. On the first one, it seems like if you bypass the first mixing valve you'll need a second one downstream of the tank because the water in the tank could get pretty hot, esp. when you're making steam.

Mike
Thanks again Mike. I see what you are saying. I would add a second mixing valve on the outlet side of the Gas hot water heater, this way it will control the temp either way should it get too high.

 
Pacowy
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Post by Pacowy » Sun. Sep. 20, 2015 11:49 am

You're welcome. Why not just use one mixing valve that would protect either source?

Mike

 
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Vampiro
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Other Heating: POS gas boiler

Post by Vampiro » Sun. Sep. 20, 2015 12:41 pm

That's true. I also was thinking about the cold water inlet and the dip tube. I believe the dip tubes are plastic. So would I have to pipe the water into one of the taps located on the water heater to prevent melting the dip tube?

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