Temporary hot water heater on washer hookup?

[DIYorBust]

Hi Folks, I have a situation where we need to turn off our gas service for some time, which will disable the water heater. I want to temporarily connect an electric water heater. I have an unused washing machine setup near the water heater location. Fortunately, the main electrical panel is accessible nearby. I'm contemplating if I could connect an electric water heater at that location, which would save some plumbing work and materials cost. The washing machine supply lines are only half inch, but I currently have only one bathroom and one kitchen sink active in the home. With the kitchen sink and the shower running full hot, it seems like we'd still be under 5gpm. Is there any chance this idea could work?

 

[Reach4]

I think so. You are talking about supplying the WH thru the WM cold supply garden hose thread, and backfeed the WH output into the laundry GHT hot supply pipe. Maybe 3 gpm.

Temporary. No inspections.

 

[Sponsor]

 

[DIYorBust]

Thanks Reach4. Are you saying maybe 3gpm is what we need, or what the capacity of this setup would be?

 

[Reach4]

Thanks Reach4. Are you saying maybe 3gpm is what we need, or what the capacity of this setup would be?

It is about what I expect just a shower to take. How much you are going to be able to push thru will partly depend on the particular washing machine shutoff valves.

The flex washing machine supply lines that connect can be more restrictive than others too. So even 3 gpm is not certain, but I would think you can probably attain that. I tend to doubt you could get 5 GPM with more typical components.

This is going to be hokey. The water may pick up a taste in the hoses.

 

[cdherman]

Are you trying to save a few bucks by shutting off your gas over the summer months? The described setup will work I think -- but if a hose breaks and floods the basement, your homeowners policy might deny the claim. If its a one off deal, OK, but if you are contemplating this hack on a yearly basis, you are asking for an unfortunate event.

 

[DIYorBust]

Thanks again. Yes it's a one off deal, because we need to do work on the gas plumbing that will take a while. How long is not clear, but longer than we want to go without a shower. I was thinking to swap out the washing machine valves which are npt into copper with npt x npt valves, and use water heater flex connectors, since I don't feel like washing machine hoses are ideal for this purpose. We don't normally drink hot water, but I hadn't thought about the taste. The water heater flex shouldn't have that issue. Also the setup is in an unfinished area with a floor drain, it has been flooded before without serious damage, although that would never be good, but not as bad is it could be in some setups. I think we may try it, will let you know if it works.

 

[Reach4]

Water heater corrugated stainless or copper connectors are better.

 

[DIYorBust]

So we did it, and I wanted to report my findings for future forum researchers or AI tools. The installation was a success, pretty easy. We were able to use 24 inch water heater corrugated stainless connectors. Online it seems they come in up to 5 feet, but we did not need that here. Upon closer examination, it appears the washing machine valves in this case were full port ball valves, so a garden hose to 3/4 NPT adapter might have saved a little time an money, but I will try to save the extra valves for future projects. I used 1/2" NPT valves with a 1/2 in x 3/4 in brass bushing and connected the water heater connector to the bushing. There's about 4 inches of brass between the stainless and the copper. For a short period of time, maybe a couple months at most, it didn't seem worth using dielectric unions, but I'll keep an eye on that.

As for performance, it works great. I took a shower as soon as the water heated up, no issues. It's worth noting I have a thermostatic shower valve, so that may be helping with any pressure instability caused by the 1/2" pipe restriction at the water heater connection, but I did not notice any loss of pressure. I think some small homes have been plumbed entirely in 1/2" inch in the past.

In general, I feel okay about the setup and I think it's pretty unlikely to leak. A water heater is connected to the plumbing with listed water heater connectors, it's not the craziest thing I've ever seen. Unfortunately, I cannot report on how it would have performed with washing machine hoses, but I don't think there is a reason to try that experiment when water heater connectors are inexpensive and broadly available. Again this is only for an emergency temporary hot water situation, and it will be retired as soon as possible. And to be clear, I'm not recommending or suggesting it to anyone. I'll try to update if anything else interesting happens with it. Thanks again to the folks who responded here.