Tankless water heater idea!

littlebitfarm · #1 03/09/08, 11:31 AM

I have a tankless water heater. Works great in the summer but in the winter I would like hotter water. It only raises the water temperature so many degrees above it's initial temperature.

My water source is a large underground cistern, fed by my gutters. So in the summer warm water runs into it and in the winter cold water runs into it. The temperature is partially regulated by being underground. But the water is a lot colder in the winter than it is in the summer.

My thought was some way to preheat the water. I don't have a wood stove and it would be a bear to figure out some way to circulate the water through a solar setup. But I have a deep (4') crawlspace that averages probably 65º in the winter. I think that would be enough preheating to make a difference in my winter hot water temperature.

I think if I put a 10 or 20 gallon tank in the crawlspace, that water would reach 65 º and then it could got to the water heater.

My question is what can I use for a water tank?? It is a pressurized system, so I'll need a closed tank, that can be pressurized. Only thing that comes to mind is an old water heater. Any other ideas????

Thanks,

Kathie

celticfarmgal · #2 03/09/08, 11:37 AM

what size/brand tankless do you have just asking because we are thinking of going tankless

littlebitfarm · #3 03/09/08, 11:51 AM

Quote:

Originally Posted by celticfarmgal

what size/brand tankless do you have just asking because we are thinking of going tankless

It is a Bosch Aquastar 125 HX LP

Kathie

Windy in Kansas · #4 03/09/08, 12:36 PM

Tractor Supply Company (TSC) sells bare galvanized tanks that could be used. They cost about $100. You might also find that a shallow well pump tank or pressure tank at a little less money, which too would be uninsulated. More sizes available with one of those.

It is also good to remind others thinking of tankless heaters that there are different sized units which raise the temperature differently for the flow you have. It is not a one size fits all product so please don't be discouraged thinking that all might not heat hot enough.

littlebitfarm · #5 03/09/08, 12:38 PM

Could I use a large coil of reinforced tubing??

That's what connects my pressure tank to my pump, so I know it can take the pressure.

Kathie

Deborah Stephenson · #6 03/09/08, 01:21 PM

Try running extra water pipe back and forth through a large compost pile to preheat. If your heap is large enough, you may even be able to by-pass your Aquastar - that water will be pretty hot already! Or you could try making a sawdust stove (any size from a paint can to a 55 gallon barrel - or larger) with pipe coiled around the outside to preheat your water. Check these out for some ideas...

http://ersson.sustainabilitylane.com/greenhse.htm

http://attra.ncat.org/attra-pub/compostheatedgh.html

http://www.motherearthnews.com/Green...ust-Stove.aspx

And the follow-up to that article...
http://www.motherearthnews.com/Moder...ust-Stove.aspx

Good Luck!

littlebitfarm · #7 03/09/08, 01:35 PM

[QUOTE=Windy in Kansas;2926447]Tractor Supply Company (TSC) sells bare galvanized tanks that could be used. They cost about $100. You might also find that a shallow well pump tank or pressure tank at a little less money, which too would be uninsulated. More sizes available with one of those.QUOTE]

The problem with a pressure tank is there is only one opening. Either the water would bypass the tank totally, or it would mix with the cold water.

Kathie

littlebitfarm · #8 03/09/08, 01:38 PM

Right now my entire water system (except line to the barns) is inside and therefore I have no concerns about any freezing. I'm not interested in running any waterline outside. I want to use the heat of the crawlspace to preheat the water. Just need a way to store 20 gallons of pressurized water inside.

Kathie

SolarGary · #9 03/09/08, 08:56 PM

Hi,
One easy way would be to put a coil of the black poly pipe in the crawl space and run the water through it. This way the water in the pipe coil gets a chance to warm up before it gets to the shower. Its like a long skinny tank

A 300 ft coil of 1.25 inch diameter pipe holds about (1.25^2)(0.785)(300)(12)/(231) = 19 gallons of water.

You could use the lowest pressure rating (80psi) stuff -- but, I would get the NSF approved for drinking water stuff.
Its pretty cheap.

A drain back type solar heating system would be pretty simple.
1 collector, something like a Taco 008 pump, and a goldline GL30 differential controller could be the whole thing.
But, it might get the cistern water hotter than you want -- not sure.
http://www.builditsolar.com/Projects...0Closed%20Loop

Gary

littlebitfarm · #10 03/10/08, 08:09 AM

Quote:

Originally Posted by SolarGary

Hi,
One easy way would be to put a coil of the black poly pipe in the crawl space and run the water through it. This way the water in the pipe coil gets a chance to warm up before it gets to the shower. Its like a long skinny tank

A 300 ft coil of 1.25 inch diameter pipe holds about (1.25^2)(0.785)(300)(12)/(231) = 19 gallons of water.

Gary

Thanks Gary! I was also considering 40' of 4" PVC pipe which would get me 26 gallons of storage. But I think the small hose would give me the maximum time to warm without the ability to mix or bypass!

I've worked with that black poly pipe before. Should be easy!

Kathie

WisJim · #11 03/10/08, 08:40 AM

Rather than a coil of black poly pipe or 4" PVC, I would use a 100 feet or more of 3/4" PEX tubing. The pex is designed for potable water at higher pressure and can take a bit of freezing. We use an extra water heater as a preheater in the basement--I got it at a garage sale, just a couple of years old, but the people had switched to natural gas when the gas lines were put in past their house, and sold the almost new water heater really cheap. Whatever you decide to do, a preheater of this type should help a lot.

Edited to add: I am not sure what kind of pressure the 4"PVC would take, or if it is approved for supply lines (I am thinking it is just for drain and waste piping). Same with the black poly, although the poly does come in different grades and pressure ratings, and some 1 1/4 or 1 1/2 inch black poly rated for over 100psi and food grade or for potable water would hold more than a smaller size. I would say use what you can fit in the space easily, coiled so that it is supported to carry the water weight, and so that air can circulate around it well to warm the water. It seems to me that the pipe or tubing would preheat the water better than a tank would--I use a tank because it was so cheap.

SolarGary · #12 03/10/08, 09:39 AM

Quote:

Originally Posted by WisJim

Rather than a coil of black poly pipe or 4" PVC, I would use a 100 feet or more of 3/4" PEX tubing. The pex is designed for potable water at higher pressure and can take a bit of freezing. We use an extra water heater as a preheater in the basement--I got it at a garage sale, just a couple of years old, but the people had switched to natural gas when the gas lines were put in past their house, and sold the almost new water heater really cheap. Whatever you decide to do, a preheater of this type should help a lot.

Edited to add: I am not sure what kind of pressure the 4"PVC would take, or if it is approved for supply lines (I am thinking it is just for drain and waste piping). Same with the black poly, although the poly does come in different grades and pressure ratings, and some 1 1/4 or 1 1/2 inch black poly rated for over 100psi and food grade or for potable water would hold more than a smaller size. I would say use what you can fit in the space easily, coiled so that it is supported to carry the water weight, and so that air can circulate around it well to warm the water. It seems to me that the pipe or tubing would preheat the water better than a tank would--I use a tank because it was so cheap.

Hi,
The black poly pipe with the NSF stamp on it is intended for potable water.
Its very commonly used around here for piping from the well to the house and the like.
Good point on the greater surface area of the pipe making for faster preheating than a tank.

Gary

texican · #13 03/10/08, 11:37 AM

Might be cheaper to just get a larger tankless... or get two, and turn one off in the summertime.

My Survivalist side of me recommends investing in an alternative means of heating your water, as 'outside' fuels won't last forever (electrics, natural gas or propane)... Develop a wood burning system, or a solar heat system....

theuniquey · #14 03/10/08, 09:08 PM

I totally agree with Texican on the wood and/or solar options. I've been looking at different types of batch heaters and there's a lot of really good ideas out there

alidansma · #15 03/11/08, 12:10 AM

just a note about our tankless experience. This winter we got pretty cold, to the point where our shower was 80-85 degrees - tops. It was miserable.
We learned that the tankess water heater we had was meant to be ran with a dedicated 1" line - not the 3/4" we had running through out the house.
Seems the 3/4" just couldn't get enough propane to the unit to make it work right.

We ended up going back to a regular storage type water heater. It was the cheapest option we had at a moments notice. I really liked the tankless, but three weeks without a hot shower in the winter was not a lot of fun.