Detached garage water heater

[pgray007]

I’ve managed to think, and then overthink hot water in my detached garage a dozen times and would like some advice.

Had I been a bit wiser I would have had a hot water line run from our house to my detached garage and put a ~5 gal point of use tank on the line to cover the few minutes for hot water to get to the shop. But I was at least 84% less smart when the shop was built, so I have a single cold water feed to the shop and no reasonable way to get a hot water line out there.

Shop is 2 floors, with a slop sink in the garage, and bath, shower, and bar in the upstairs. Probably ~4 weeks per year we’ll have guests staying there, and they’re generally family who loves long hot showers. The rest of the time it’s likely hand washing and sink use mostly.

I’ve thought about everything from multiple POU water heaters, to RV-style 20 gal units, up to a full scale 50 gal hybrid unit and as soon as I talk myself into one solution the price, space, cost to run, or some other factor talks me back out. Anyone have a good solution to a similar situation?


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[75gmck25]

Considering the infrequent use, I think I'd probably install a standard 40 gallon electric, and then put it on a timer/switch. These heaters are relatively inexpensive up front, and there are ways to reduce the per-month cost.

For example, you can insulate the tank, buy an electric water heater timer/switch, and limit normal on-time to a couple of hours a day. When guests are using it you can either manually switch it on, or just reset the timer for a longer on-time.

I have done this in my own house when I had an electric water heater, and found that if it was on from about 5:00 AM to 7:00 AM (getting ready for work/school), and then from about 5:00 PM to 7:00 PM (supper prep and cleanup), we always had enough hot water. On weekends and holidays I would just flip the switch manually to on when it shut off at 7:00 in the morning, and we had normal hot water all day until it shut off again at 7:00 PM.

Bruce

 

[Thumper68]

Funny this should come up, I just turned off the water heater in the shop a few weeks back and was contemplating it again this morning as I was washing my hands in the very cold water.

I have a 40gal electric because we have a shower in the shop and over the summer it gets used a lot, but during the winter I am the only one who ever uses it, and that may only be 2 or 3 times over 9 months.

Today I decided that I can deal with washing my hands in cold water and save the $$$ for those months.


As I was typing this I decided that I am going to flush and drain the heater, good time to do it now before it gets to cold out.

 

[dw1]

I just installed an on demand electric water heater in my barn, I only have electric and this is somewhat temporary until we get a house built, then I will turn it off and drain it. It is on a 70 amp circuit but it works great, the one I bought is a Marley ECO150xx. it was cheaper than a short 30 gallon tank, but also I didn't want a tank, not sure if it will get used after the house is built. IOt is serving its purpose.

 

[pgray007]

My plan (for this minute anyway) is to do a 30 gallon on a Zwave switch so I can tie it into the garage automation system, and hopefully add some intelligence so that it only spools up when needed. I’ll also do a 2-4 gallon POU under the slop sink, so I can get warm water for shop tasks without waiting for the big guy to heat up.

Only thing I don’t like about this plan is that I’ll loose some floor space to the tank, but the alternatives (using half the shop panel for a tankless, hanging a 20 gal from the ceiling, etc) don’t seem particularly appealing either.


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[yeldogt]

We have had many discussion regarding on demand WH -- this is a good test case.

It sounds like you may not have NG at the location .. if you did, a tank would most likely be the way to go for overall 10 year cost calculation.

If you have the amps -- an on demand electric would be perfect... it would give you the hot water when you need it in the shop and also give you the capacity when people are staying over ... in between it would cost you nothing.

The other possibility is to have a small 2 or 5 gallon tank with a larger 30-40 gallon tank in series before it -- the larger tank can be turned on when guests are around. I have a 10 gallon 110v tank out at the outdoor kitchen and we never run out just doing normal prep and clean up.

 

[mrobins297aaa]

I've posted this before but this is what I did, I ran just a single cold water line to my barn and used a instant water heater that I run off of a propane bar bq tank.
I was just to far from my house/water heater to run a hot water line.
it works great, mostly I use it for washing cars and my hands.
it's nice because there is no standing water in it, sometimes it might be a couple of weeks in between use.

 

[pgray007]

I've posted this before but this is what I did, I ran just a single cold water line to my barn and used a instant water heater that I run off of a propane bar bq tank.

I was just to far from my house/water heater to run a hot water line.

it works great, mostly I use it for washing cars and my hands.

it's nice because there is no standing water in it, sometimes it might be a couple of weeks in between use.

How long before you need to replace the tank? Would that sucker provide enough hot water for a shower?


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[yeldogt]

I've posted this before but this is what I did, I ran just a single cold water line to my barn and used a instant water heater that I run off of a propane bar bq tank.
I was just to far from my house/water heater to run a hot water line.
it works great, mostly I use it for washing cars and my hands.
it's nice because there is no standing water in it, sometimes it might be a couple of weeks in between use.

Interesting solution .. it would never pass around me.

The OP could do it with a typical outside 100g tank and get deliveries .... he does not say how he heats his building.

 

[mpire]

Not sure this applies, but maybe it would be helpful.

My master shower takes forever to heat up, I guess because its the farthest from the hot water heater.

I got a hot water to cold water line re-circulation pump and then put it on the same switch as the ceiling light. That way it runs whenever I turn on the bathroom light. Gives it a minute to heat up the water by pumping it into the cold water line. So when I turn on the shower its already hot. Doesn't waste water, and is convenient. I can also turn it off with another switch.

 

[pgray007]

Interesting solution .. it would never pass around me.



The OP could do it with a typical outside 100g tank and get deliveries .... he does not say how he heats his building.

I’ve got a mini split doing heat and cooling. We have gas to the house, but running a line to the detached would get pretty expensive.


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[mrobins297aaa]

How long before you need to replace the tank? Would that sucker provide enough hot water for a shower?


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I put that tank on in early may this year and it still has some gas left in it.
I'll be turning the water off to the barn in about two weeks for the winter, so for my needs it lasts all season.

I think it would supply enough hot water for a shower but I think you would run into a problem with that 20# tank not making enough vapor, now maybe if you had a 50# or even a 100# tank it might work very well.

The unit I have is a Eccotemp FVI-12, it's 75,000 BTU's, I have just a standard bar bq regulator on it that I bought from Homedepot (there good for about 75,000 BTU's)
I 've had it for about 5 years, I think I paid around $250 for it. you can look it up on ebay most of the auctions have all the spec' like gallons per minute of hot water etc.

If you need to have the install inspected the only thing I have there that would not pass code is the propane tank should be outside, otherwise it would pass.