Run hot water from 2 separate water heaters to one washing machine.

[Lane75]

I have a two family property renting both units. We supply a washing machine and dryer in the basement for both tenants to use. Currently we only have cold water running to the washer but I'm wanting to run hot water to it as well. The issue is each tenant has there own water heater and they pay that electric bill. I don't want to spend a lot of money and rather then run hot water from just one water heater to the washing machine making only one tenant pay for that, I was wondering if I could just tap in to each units hot water lines, joining them and then run that line to the washing machine. That way each unit would pay for the hot water. I've also thought about installing a tankless water heater just for the washing machine but didn't really want to spend the money since I'll also have to add a 240 outlet as well.
Is it OK or acceptable to run a line from two water heaters being used by two different appartments and run it to one washing machine? With pex and shark bites something like this wouldn't be too difficult.
Thanks for any help.

 

[Dana]

How are you going to guarantee that the flow from each water heater is the same? You'd have to carefully measure the lengths and number of ells on each run to match, including the cold feeds to the respective water heaters to have reasonable assurance that it's anywhere near a truly balanced flow.

How do you intend to split the operating costs of the dryer (be it gas or electric) between tenants?

Putting the dryer onto one tenant's utilities and the washer on the other tenant's is probably about as good as you're going to do in this situation. It won't be anywhere near perfect, but nothing really is.

I'm not sure if there is anything in MA statute or regulations (or even town regulations) that addresses this issue.

Electric tankless water heaters don't solve the "who pays" issue, and it requires some hefty wiring to run it, independent of the volatage.

If having a local hot water heater makes the plumbing significantly easier or solves some other problem, a small 120 VAC electric tanks large enough to fill the washer would work. A 15 gallon 2000 watt 120VAC tank would usually be enough. It would need a dedicated breaker, but nothing special for wiring or breaker capacity- a standard 20 amp circuit covers it.

 

[Sponsor]

 

[Lane75]

How are you going to guarantee that the flow from each water heater is the same? You'd have to carefully measure the lengths and number of ells on each run to match, including the cold feeds to the respective water heaters to have reasonable assurance that it's anywhere near a truly balanced flow.

How do you intend to split the operating costs of the dryer (be it gas or electric) between tenants?

Putting the dryer onto one tenant's utilities and the washer on the other tenant's is probably about as good as you're going to do in this situation. It won't be anywhere near perfect, but nothing really is.

I'm not sure if there is anything in MA statute or regulations (or even town regulations) that addresses this issue.

Electric tankless water heaters don't solve the "who pays" issue, and it requires some hefty wiring to run it, independent of the volatage.

If having a local hot water heater makes the plumbing significantly easier or solves some other problem, a small 120 VAC electric tanks large enough to fill the washer would work. A 15 gallon 2000 watt 120VAC tank would usually be enough. It would need a dedicated breaker, but nothing special for wiring or breaker capacity- a standard 20 amp circuit covers it.

Thanks for the reply. The dryer has a 220 outlet which runs off the public meter paid by me. The property is supplied from the city water supply so I was thinking pressure would be the same as both lines would be pretty much the same length and size coming from each tank but of course considering who is using hot water at what time could affect which water heater is being used the most.
The solution of the tank less water heater would have been that it would be coming from the cold water supply which is paid by me and the outlet would have also been paid by me going to the public electrical meter. One I was looking at requires a 60 amp breaker. I mainly just don't want to spend the money but will if I have to.
I'm just not sure if there was a plumbing physics or safety reason I'm not aware of that would make using both water heaters for one washer a bad idea.

 

[Reach4]

I was thinking that each unit could supply water, through a valve they control, through a tee to the washer. You may want to have a check valve (one way valve) in place in each pipe in case both valves are open at the same time. I am not a pro. Just thinking.

 

[Lane75]

I was thinking that each unit could supply water, through a valve they control, through a tee to the washer. You may want to have a check valve (one way valve) in place in each pipe in case both valves are open at the same time. I am not a pro. Just thinking.

That's not a bad idea and definitely cost affective. I guess it would then be a trust issue as to remembering to turn the other units off and turn your's on each time you did laundry. Thanks for the response.

 

[Reach4]

That's not a bad idea and definitely cost affective. I guess it would then be a trust issue as to remembering to turn the other units off and turn your's on each time you did laundry. Thanks for the response.

If separate valves are in the separate units, no trust required other than trusting your memory.

You may want to run the hot also to the nearby laundry sink. I like to run the hot into the laundry sink before starting the cycle if I want the hottest water to fill the machine.

 

[WorthFlorida]

If your renters are one or two people each, the cost per month for them to do laundry is very small on the meters and you hardly will notice it on your bill. Besides, it would be a good reason for them to stay with such a friendly landlord. If one of your tenants has five kids it would be a different story. If you do go with this crazy scheme, at least place check valves from each hot water line so as to prevent heated water going in the wrong direction should pressure drop on one side. The simplest solution is install two sets of washing machine and dryer connecting to the respective water lines and electric for each tenant. Either way it will probably cost you more than what it would cost for them to use your hot water and electric for a year.

 

[Dana]

It would be a lot easier to just add local 15 gallon - 40 gallon (whichever is cheaper) hot water heater serving the washer to the same power meter as the dryer. The standby loss of a legal-efficiency hot water heater these days is on the order of 35 kwh per month, or about $7/month, or $85/year at MA type residential retail pricing (less, if you're on one of the municipal light companies, in most cases.) The bulk of the operating cost is the actual heating of the hot water, but I'd be surprised if it ended up being anywhere near $1000/year total if it's only feeding the washing machine (unless you get a tenant who is a compulsive clothes washer running several loads per day, every day.)

The payoff for the up-sized cost of a tankless with it's very-low standby loss is pretty much "never".

The separate valves behind locked doors approach would work, but would probably be a real PITA from the tenants' point of view.

The city pressure is the same to both units, but for balanced flow you have to guarantee that the plumbing impedance is also well matched, which is why both the cold feeds to the water heaters and the plumbing runs from the water heaters to the washer match in both pipe diameter and length of the pipes, being mindful of the "equivalent length" of any tees & ells. Even that isn't going to work all that well, since a hot water draw from another tap when the washer is drawing will reduce the flow to the washer from the side with the second draw.