Plumbing – Connecting a water heater, what kind of fittings, valves, and adapters

plumbingwater-heater

I'm buying a new water heater, and quite frankly the series of connections and valves are mind boggling. What I'd like to do rather than soldier the pipes together is to go from compression to thread. I have 3/4 ID (inner diameter), 7/8 OD (outer diameter) feeding the water heater. From that point there are a series of elbows and a valve I don't trust taking the copper pipe to the water heater.

I'd like to cut them off, and put on a compression fitting and flex tube to the water heater. Is there anything wrong with this idea? Moreover, what kind of valves and adapters do I use?

Ideally, there would be a combo-valve that would go from 3/4 compression to thread, and then from a mail thread I could use a flex pipe to go right to the heater.. This valve doesn't exist, but such a setup would result in one compression rings per water line.

What does exist is compression-compression-valves, but in this configuration I'm adding two more compression rings per side of the water heater which is far from ideal. I assume this is a bad idea? I've ruled this out.

So, it seems I could go from 3/4 to NPT right away. Then I could use Female NPT-NPT valve. But, I can't find the 3/4-3/4 male NPT coupling fitting to tie the female flex pipe into the female valve.

3/4 pipe → 3/4 compression female to NPT male → NPT female to NPT female valve → NPT female valve to NPT male-male coupling → NPT male-male coupling to NPT female flex pipe.

And none of these parts are carried by anyone retail store… So what's the right and easy way to do this? I've had very good luck with compression fittings.

Best Answer

Assuming that your HWT connections are 3/4 MIP and starting from the tank working back the the pipe at the wall:

Cold Side

  1. 3/4 FIP x 3/4 MIP Flex Hose

3/4 FIP x 3/4 MIP Flex Hose

  1. 3/4 Threaded Ball Valve

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  1. 7/8 x 3/4 Brass Compression x MPT Adapter

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Hot Side

  1. 3/4 FIP x 3/4 FIP Flex Hose

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  1. 7/8 x 3/4 Brass Compression x MPT Adapter

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(No need for valve as the valve on the cold will isolate the hot)

No need to use these particular brands, they are just the first ones I found. All items should be available on Amazon or a local hardware store.