plan to resolve heat loss

[tapenick]

Hello,
Tom here, new to this forum. I think I have an unusual plumbing problem:

When it rains, especially when it's cold out, we don't have hot water in our back bathrooms.

Weird huh? Slab home, only thing I can think of is that there's ground water under the slab that's cooling the water in the pipes as it travels from the water heater. (which is at the other end of the house)

So, I thought about putting in a sump pump. Or, put tankless hot water heaters in the attic above the showers.

Thoughts?



Thanks in advance,
Tom

[paul52446m]

Are you in a area where it will freeze in your attic, or can you build it into a little room in the attic? I think the tankless hot water heater would be better than trying to put in a sump pump.
You sure would not want to wash any dirt out from under your slab. later paul

[tapenick]

Thanks for the reply Paul. I'm in north Alabama so not much chance of freezing in the attic. Good point on the sump pump moving dirt from under the slab. Thanks!

[pushkins]

The only way you could utilize a sump pump would be near the slab not under it, how would you get the pump under the slab ? Cutting a hole in the slab to try to install a pump would be a bad idea all round. A pump beside the slab would also become problematic as any hole you dig will become a place for "all" water to go to. Correct drainage away from the home is the best place to start.
If all your pipes run in the concrete how do you intend to add a hot water system at the bedroom end of the house ?, your going to be in for some serious work cutting, capping and re running new lines.
Are you sure the lines run in or under the slab, this is an unusual way to run either hot or cold lines (unless for heating) ?

[tapenick]

The only way you could utilize a sump pump would be near the slab not under it, how would you get the pump under the slab ? Cutting a hole in the slab to try to install a pump would be a bad idea all round. A pump beside the slab would also become problematic as any hole you dig will become a place for "all" water to go to.

Wasn't planning on putting the pump under the slab, just beside it. Realized that wasn't ideal, that was part of the reason for not using that idea.

Correct drainage away from the home is the best place to start.

So would this be french drains going away from the house? Another odd thing is that the house is on a high spot, ground slopes away on all sides. That just for the immediate area.. say 100 - 200 feet. It is lower than most of the houses in the neighborhood. No standing water though.

If all your pipes run in the concrete how do you intend to add a hot water system at the bedroom end of the house ?, your going to be in for some serious work cutting, capping and re running new lines.

They actually run in the gravel under the concrete. But that doesn't matter, the plan was to cap the hot water line at the fixture, extend the cold water line into the attic, connect to hot water heater, route output line from heater back to fixture. I know that's hokie but it was all I had came up with.

Are you sure the lines run in or under the slab, this is an unusual way to run either hot or cold lines (unless for heating) ?

Pretty sure. That's the way I thought they did plumbing for slab construction in this area and since we figured out the scenario that caused cold showers (rainy and cold) I've been asking around and it is the consensus.

Thanks for the reply, let me know more thoughts on the correct way to solve this.



Tom

[Redwood]

You are correct that the long distance underground has ground water soaking all the heat out of your hot water. Your house is not a u-shape by any chance?

I would reroute the hot supply through the attic to the affected bathrooms.
Keep the lines on top of the ceiling and under the insulation you should be fine.

[tapenick]

Your house is not a u-shape by any chance?

Sort of a U-shape.. attaching a diagram of the house with the locations of the showers and hot water heater.

Not to scale or perfectly accurate but hopefully close enough.

So what's the thinking on the U-shape?


Tom

[pushkins]

Redwood is onto the best and most economical solution, if your kitchen is near the hot water tank and not effected then you may not want to try to redo that one as you'd need to probably remove a cabinet to get into the wall behind the sink to make new connections but you might get away with capping off the hot at the other end of the house and teeing off the hot at the hot water tank up into the attic then back down to the bathrooms (like he suggested).

[Redwood]

I just seems like they have a tendency to be the ones with the problem. They always have the water heater at one end of the u and the bathroom with the cold hot water at the other end...

Call it an educated guess!

[paul52446m]

If you want hot water fast at the other end of the house, and you have a attic that will not freeze. You could run a new main from the water heater through the attic and a return line,
insulate them , pitch them and tie the return back into the bottom of the heater with a swing check valve. This way it can gravity flow and you have hot water fast.
later Paul

[citydrains]

heating issue

The problem only occurs when it rains? During the rain or directly after? If after, how long after?