Water heaters in the attic...thoughts?

[GeorgeG.]

While we were looking at new homes, I noticed a few that are putting water heaters in the attic. Deep down, I don't think this is a good idea but I'm wondering why a home builder would think so.

In past houses we've lived in, the WH was always in the garage. This made me have to run the water in the bathroom for a while just to get hot water to that side of the house, which seemed like a ton of wasted water.

The new house we're in the process of designing, has the WH in the garage and the master bedroom on the other side of the house. I'd like to conserve water but the only way I see to do this is to put it in the attic. I can't imagine how much of a PITA it will be when it comes time to replace it, IF you catch it before it ruins your house.

Any thoughts on this? Russell, are you guys putting them in the attic in your builds?

[8mpg]

Bad idea... if you develop a good leak, you ruin your insulation and ceiling. Its a bitch to change out. Some of these new efficient heat pump water heaters are heavier than hell.

Id rather lose a little closet space or whatever to have a mechanical closet. Use a pex manifold with some 1/2" lines. Mine pipes off the manifold to the master bath (shower specifically) and is about a 45' run. I have hot water in 12 seconds (yes I counted many times). These manifolds are awesome. If you have a leak, shut off one sink, or one toilet or one shower. Dont have to shut off water to the whole house.


Builders do it because people want every bit of living space possible and its not their problem to change them and fix the ceiling if the thing leaks.

[mstng86]

whats wrong with doing a tankless water heater?

[LS1Goat]

Mine is in the attic with a leak detection alarm. I'm not necessarily happy about it, but this is very common. The standard size 2 car garage is too small and people don't generally want to give up inside closet space. There is one advantage to having it in the attic in hotter climates, like Texas. Takes about 5 seconds to get hot water in my master bath.

[8mpg]

whats wrong with doing a tankless water heater?

yearly descaling that nobody does, electric ones are not that efficient, electric ones need huge power (60-100amps) dedicated and can cost a lot to run the power. They are also expensive

Mine is in the attic with a leak detection alarm. I'm not necessarily happy about it, but this is very common. The standard size 2 car garage is too small and people don't generally want to give up inside closet space. There is one advantage to having it in the attic in hotter climates, like Texas. Takes about 5 seconds to get hot water in my master bath.

He is way better off running a sealed attic with a spray foamed roof line to run his a/c ducting in rather than a traditional attic and a water heater in it. He will save much more money (studies show 25% cooling loss with a/c ducting in the attic). Im a believer in heat pump water heaters that are 2-3 times more efficient than a traditional water heater and only cost $200 a year to run

[GeorgeG.]

whats wrong with doing a tankless water heater?

I thought about it since I will have propane but I from what I discovered from previous threads on here is that they're expensive and it takes a long time to reach your ROI. Plus, since the new regulations were passed recently, the new tanks are suppose to be far more efficient. I'm not really worried about hot water demand as much as wasting water while waiting for it.

yearly descaling that nobody does, electric ones are not that efficient, electric ones need huge power (60-100amps) dedicated and can cost a lot to run the power. They are also expensive

I wasn't aware of any descaling requirements... but yeah, I probably wouldn't do it either.


He is way better off running a sealed attic with a spray foamed roof line to run his a/c ducting in rather than a traditional attic and a water heater in it. He will save much more money (studies show 25% cooling loss with a/c ducting in the attic). Im a believer in heat pump water heaters that are 2-3 times more efficient than a traditional water heater and only cost $200 a year to run

Can you elaborate on this? Are you referring to spray foaming the entire roof decking? I'm going to save that manifold pic so I can bring it up once it's time to meet with the plumber.

[black2002ls]

We have a few plans where they are in the attic. There are a couple of things that come into play as to why.

Architects don't seem to have enough foresight to see that this is a bad idea, and thatvthey need to allow for some kind of mechanical chase/clearance for the flew pipe in gas communities.

The other part of it is the HOA/developer. A lot of them mandate that vent stack can not exit through the roof on a front elevation. We move them to the garage whenever possible, again we only have a few plans where this applies).

As for leak detection, that only offers minimal security. In the event of a tank rupture, you are guaranteed 40+ gallons per tank coming down. The drain pans aren't going to help in those instances, and the leak detection sensor/shut off is only going to close the supply line, not stop the 50 gallons of water coming out!

I actually ran i to this with a homeowner during pre-construction on Tuesday. We generally suggest a tankless heater.

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[LANTIRN]

They suck. Our new build is in the garage and does not take up much room. My parents moved a little over a year ago and theirs is in the attic; house is about 5 years old. Guess what dad and I did about 3 weeks ago? It was a pain in the ass. Turns out since the house was built they apparently changed regs on what size the heaters have to be. They are physically larger now and there is not enough clearance for the new ones to fit if you get the same size in gallons. He lucked out and bought the last one in stock of the old size. Not sure what we will do next time. On top of that there was just enough clearance in width in the attic access to get them in/out. Even empty they are not light and I was on bottome pushing with the damned thing getting jammed so it just sucked. Plus it was July in Texas in the afternoon. I would avoid one in the attic if possible unless the rest of the house was your dream property or it was a smoking deal. Wouldn't necessarily be a deal breaker but it would be something to try and avoid.

[mstng86]

So whats wrong with having an outside, enclosed, insulated box for the water heater right next to your house?

It would be no different than being in a un-insulated hot box like the attic and garage.

[LANTIRN]

So whats wrong with having an outside, enclosed, insulated box for the water heater right next to your house?

It would be no different than being in a un-insulated hot box like the attic and garage.

I am sure alot of towns have codes against stuff like that. If not you can bet HOAs won't allow it. Good idea though. I would rather have it there than in the house so it doesn't ruin shit when it leaks.

[8mpg]

I thought about it since I will have propane but I from what I discovered from previous threads on here is that they're expensive and it takes a long time to reach your ROI. Plus, since the new regulations were passed recently, the new tanks are suppose to be far more efficient. I'm not really worried about hot water demand as much as wasting water while waiting for it.



Can you elaborate on this? Are you referring to spray foaming the entire roof decking? I'm going to save that manifold pic so I can bring it up once it's time to meet with the plumber.

Time to do some major research man... its all about building science in my opinion. My house is 2100sqft and I run my ac at 73*f and my electric bill was $75 last month..

Most houses in Texas run a traditional hot attic that is vented. Soffit vents and wind turbines on the roof, and an assload of blown in fiberglass insulation. Its cheap and kinda works. They neglect to put the heating/ac in a conditioned space so you lose 25% of your heating and cooling to the attic between leaks and just sheer temperature difference.

Newer houses (where people try a little harder) run sealed attics. Spray foam along the roof and down into the eves. You are trying to air seal your attic 100% so no air comes in or out. My attic runs about 2-3* warmer than my living areas. This keeps the ducting and a/c in a "semi conditioned" space where its the ducting is moving 55* air in a 75* attic vs 55* air in a 120* attic.

It costs a little more to spray foam the roof line over a traditional insulation but totally worth it in my opinion. I have 40sq roof and it was just under $4k for them to do 7" of spray foam (open cell). It would have cost about $1500 for soffit vents, turbines and 18-24" of blown in insulation. So it costs more but Im saving an easy $100/mo on my heating/cooling.

Regardless of doing a sealed or vented attic, Id recommend you definitely get a Manual J done on your house. Its $200-300 engineering report to calculate the proper size a/c unit. You will need to supply lots of info (window efficiency, insulation, which way the house faces, door types, etc). Dont let your a/c guy do a "rule of thumb" when it comes to finding the right a/c unit size. My house would have called for a 4 ton and I have a 2.5 which is plenty.


edit// Watch all of this guys Youtube videos when you get time. Hes a ton of knowledge about building houses here in the South. You will learn most of what you need to know about proper air and water sealing:

https://www.youtube.com/user/MattRisinger

[black2002ls]

On the tankless heaters. We install rinnai units, our cost to the homeowner is $1800. And we have a 30% markup figured in there. So the cost isn't too bad if you consider the potential cost of repairs and replacement if a unit in the attic fails. I have no clue what model number or specific unit we install though. I have yet to put one in any of my builds.

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[GeorgeG.]

Thanks for the tip 8mpg (and everyone else)...time to do some homework! I'm definitely not going with the tank in the attic. I never liked the idea to begin with. Space wasn't an issue, just trying to not waste water and get the hot water to the shower quicker.

[mstng86]

I am sure alot of towns have codes against stuff like that. If not you can bet HOAs won't allow it. Good idea though. I would rather have it there than in the house so it doesn't ruin shit when it leaks.

I don't see how I woul be a problem if it was bricked on the outside. I just don't understand why the garage was the next logical solution in the dresign of homes

[8mpg]

Thanks for the tip 8mpg (and everyone else)...time to do some homework! I'm definitely not going with the tank in the attic. I never liked the idea to begin with. Space wasn't an issue, just trying to not waste water and get the hot water to the shower quicker.

No problem man... If you are going to build a house and keep it, do it right. Do your research on air sealing and insulation. Exterior rigid foam 1-2" on the outside will do a lot more for you than fiberglass batt, spray cellulose and possibly spray foam walls. Its r-7 per inch but more importantly with taped seams it will really air seal the house. You want to build your house as tight as possible and if you need to bring in outside air, use an ERV to bring in clean filtered air. This is the ONLY time to really do it right.

Oh, and add a whole home filter to your a/c. Changing a single 4" air filter every 6-12 months beats changing individual filters at each air return every couple months. Its cheap to add.


My quick list of things I would do if I was building:
1-2" of exterior rigid foam (Im not a fan of the sheer rated foam. Id rather do zip panels and add insulation taping all seams)
spray foam roof line with minimal roof penetrations
Engineered a/c report (manual J and manual D)
Caulk all floor to stud, stud to stud (including double top plates)and corners
Spray foam all wiring and low voltage holes in the wall top plates and floors
Proper seals of all exterior penetrations in the walls (hose bibs, electrical outlets)
Water proofing membrane on all showers and tubs (Laticrete Hydroban or Kerdi)
Tubs must have tiling lip
Decent window SHGC and u-factor values
Exterior swing french doors (better seals)
maybe more things but thats the main ones for now.