hot water heating from hotwater tank

Joe Brix

your current heating system can't supply the neaded BTU's?
Many systems are over sized to begin with. Bradford White also makes a HW heater with an internal coil heat exchanger.

zeke

hotwater heating from hot water tank

I would like to add additional heating to my basement in a cost effective way. Electrical is way too expensive at 16 cents/KWH. I need about 7000BTUH of heat and was thinking that I could use my hot water heater as a source. Since the water is at 140 F, what do you professionals think about the feasibility of this idea. If it is, then how do I size the heater.
Thank you very much for your input.

Michal

There are water heaters that

There are water heaters that can do space heating and domestic water as well. look into like the AO Smith promax sl series, They are made with a internal coil just for space heating and it DOES NOT VOID warranty, these are natural gas fired. There are a few other manufacturers as well that make similar tanks

Craig Bergman

DO NOT...

run the domestic water through the radiant tubing!!!
Some areas of the country will allow this to be done, but I think you are asking for trouble. Would you want to drink the water that comes back from the radiant tubing after it has sat there all summer? Tekmar's new tN4 controls will allow you to "flush" the radiant tubing but that will cost more than adding a dedicated water heater for the radiant.

Bergy

Michal

Thats why I wrote the

AO Smith Tank, they have a independent coil dedicated to heating. Adding a hot water heater for any space heating purpose automatically voids any warranty unless it was designed to do domestic and space heating. But Yes, do not just tap a line of the hot water heater be it radiant or baseboard

zeke

hotwater heating etc

Thanks to you all.
Bergy:
First, if I have a check valve in the cold water line just upstream from the loop tap , do you think I would still have a cold water contamination problem? Backleakage thru the checkvalve?
Michal and Brix:
I also like the idea of independently controlling the basement temp with a thermostatically controlled circulator;this is not feasible now since I would have to add another zone for a single room. And I am not concerned about the warranty voiding you mention, unless there is a fundamental reason that it would cause premature tank damage.

Michal

under no situation

shall you mix potable water and heating water, if you do this you need a circulator by code made of bronze, as mentioned earlier, adding a single zone with a zone valve is a better way to go and changing controls around. but the mere idea of just doing what you state, I would not. Its not healthy, and is against code in many states. if you really want to do this change the tank to one made for seperate heating? and why dont you just want to tap off the boiler, thats basically what you are doing but off the HWH. get a electric zone valve and redo the controls. but do not just tap off the HWH. and second 140 hw is way too hot for a residential house, hope you have a mixing valve on hot water side. I will be honest, your asking for trouble by doing what you are thinking of doing.

zeke

Michal
Thanks again for your insight.
But,if I put a check valve in the cold water line feeding the HW heater and downstream , between the CV and the HW tank, tap the line forming a loop thru the circ pump and the heating unit and close the loop to the hot water line, I don't see any mixing with potable cold water, only the hot water which is not potable.
Where did I go wrong?
By the way, I have no boiler and natuaral gas is not available

Michal

well then

If you feel comfortable you can do that. but in all honesty the right way is to get either a electric boiler with a side coil or fine tube electric, or a small electric boiler. so there are my ideas, thats all I have

Jason_15

Propane?

What do you have? A propane or oil forced air furnace, and a propane or oil water heater?

Michal

jason

he has a electric water heater and wants to tap a line for heating. Although putting in a propane tank and a propane direct vent water heater with a internal coil might be cheaper in the long run

Cosmo_3

Domestic hot water not potable?

Huh? Let me say I am not out to make fun of you, however if you plan on using a circ to move the water from the tank to the radiant loop, that water does eventually go back into the water heater no? Then what does the backflow preventer do for you?

Keep it simple, Potable water and heating system water MUST NEVER MIX. (emphasis on the period)

I also do NOT agree with using a mechanical/electrical/control/etc because if (when) said device is not working then what? When will you find out it is not working, after is has not flushed the pipe for 6 months?

A water heater will work when the btu demand is low, but is not a long term solution, and a water heater is not certified for use as a boiler. That is why we call a boiler a boiler, end of story. Yes, you may see here on the wall that we professionals tinker around with our own houses to experiment, but it does not mean that it is proper. We just all know we have to do it the right way before we sell the house!!!!



Cosmo Valavanis

Dependable P.H.C. Inc.

Jason_15

oil

He must have oil forced air for the rest of the house then. He said electric was too expensive for heat in his area, so why tap into an electric water heater anyway? Besides all the other problems you would be "burning up" expensive electricity. Why not just run some more ducting from the oil burner to heat the basement?

zeke

My HW heater is oilfired and the checkvalve would prevent the circulating water from entering the cold water supply and possibly contaminating it. I would not sell the house with this system. Finally, I know that I could tap another vent off my forced hotair system, but as I pointed out, another zone would not be possible, so that I would still not be able to control the basement room temp.
Thank you all for a very lively discussion. I will consider what you all have said and would welcome and appeciate further input.

zeke

OIl forced air heating and oil HW heater from tank. Thank you.

Joe_20

Potable water......

Potable water is potable water, whether it's coming from a cold water source or hot water source.....Your check valve will protect the incoming cold water supply, but you still have hot water coming out of your taps that's coming from the tank that's supplying the heating coil.....bad, bad, bad.

my two cents

Joe Brix

The only cheaper solution

is a flat plate heat exchanger with a bronze pump on one side circulating the hot potable water and a regular cirulator on the heating zone loop. Still need an expansion tank, air elimination, etc. Not efficent as you must now keep the tank at at least 140° for baseboard. (Dangerous temp for DHW) Check out the cost of doing this. If the tank is old, might be better to buy a Bradford White Combi-cor oil-fired HWH with the internal HX coil.

bb

HX is needed

for this applicaiton. However, DHW temp is not too high if you want to ensure that legionelle is kept in check. Temps of 140 + prevent legionelle. Use a TMV on the DHW going to the house to temper it down and keep it safe.

bb

Michal

why not tap the duct system???

Zeke, we are not here to be pains, but you seem to be adament in doing what you stated in doing. But what you are thinking is not right and are not seeing the down sides of it. a check valve is not approved as a means of Backflow, if this is what you want to do, you have to install a watts backflow like the model 9d, but I still disagree with all of this Potable is potable no matter if its hot or cold. Try taping a branch duct off the main system, if you have oil heat thats the way to go. Leave the hot water heater as is. Home depot has enough duct parts to where you can do it yourself, and I am sure you have a little spare capacity on the oil unit.

Unknown

You're killing me!!!

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5407a1.htm

http://www.health.state.ny.us/nysdoh/infection/legion2.htm

http://www.q-net.net.au/~legion/Legionnaires_Disease_Position_Statement.htm

Maintaining hot water storage tanks at 120°F while often recommended for energy conservation, may not be the best for your facility.

Over the past several years, studies have indicated that warm or tepid water systems may be breeding grounds for the bacteria Legionella Pneumophila, otherwise known as Legionnaires' Disease. One way to combat this potentially deadly disease is to maintain hot water storage tanks at or above 140 degrees Fahrenheit.

The bacteria which causes Legionnaires' disease is often present in many natural freshwater sources including lakes, ponds, streams, and rivers--ultimately finding its way into domestic water systems.

Many of the outbreaks are occurring in hospitals, office buildings, hotels, and other settings.
A person can get the disease by either inhaling airborne water droplets containing Legionella or drinking Legionella-contaminated water. The risk can be high with humidifiers, showers, sinks, fountains, or whirlpool baths, for example.

While Legionella is everywhere, the mere presence of it in the water is not a cause for concern. Rapid growth, resulting in high concentrations, is essential before the water can be considered hazardous.

The key ingredients--a wet environment, the presence of oxygen and carbon dioxide, high microbial concentrations, scale and corrosion products--as well as a favorable temperature range (68 to 120 degrees Fahrenheit) must be present in order for the bacteria to reduce rapidly.

"Unfortunately, many hot water storage tanks provide an opportunity for accelerated reproduction or bio-amplification. You have to keep the water conditions at temperatures where the environment is not favorable for growth to Legionella out of the water, "Hot water should be stored at temperatures no lower than 140 degrees Fahrenheit and deliver hot water at a minimum of 122 degrees to the outlets."

While there is little chance of scalding at that temperature, an anti-scald valve can be installed at the outlet of the water heater. "An anti-scald (not a tempering valve) helps reduce the minimal risk of scalding for children or individuals with disabilities.

Keeping your facility out of risk is key to avoiding outbreaks, he added. Establishing engineering and management policies regarding the selection, installation, cleaning maintenance, inspection and sampling is a good way to keep Legionnaires' Disease out of your facility.

tpm

Don't use a check valve

in the cold water inlet. Do this test first. The next time the water heater is on an off cycle feel the cold and hot water pipes right at the heater. They will both be hot. The heat expands into the cold water line. If you use a check valve there is no place for expansion and you will get a dripping relief valve eventually. (Boilers are for comfort heat and water heaters are for domeatic hot water.)

Jason_15

Ducting

If you put ducting off the main duct, and put just a simple hand valve in you could get some control of the temp in the basement. No, it would not be a separate zone, but think how cheap and easy it would be compared to what you are proposing. And that's not even getting into the safety aspect. Plus if you just used the hot air, you wouldn't need to rip it out when you sold the house. That's the way to go IMO, unless for some odd reason you need super-precise temp. control for the basement. Then get a water heater with separate coil. You'll probably thank yourself later.

Michal

TO PUT THIS TO REST

ITS 21 TO 1 ZEKE, all same answers and same ideas, Listen to us, we have been there and done it.

Dave Yates (PAH)

I think

Zeke isn't Zeke, if you get my drift. Anyone advocating this type of application is either jerking your collective chains or needs a check-up from the neck-up.



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Cosmo_3

Sure you can zone

There are many companies out there that sell electric air dampers, you can retrofit your existing system to zone as many rooms differently as you want.

Cosmo Valavanis

Dependable P.H.C. Inc.

zeke

Joe, Yes , I will wait for my HWH to conk out (its 14 years old) or maybe push it to conk out.
Thanks for your input

zeke

Michal and others:
Let me thank each and everyone who responded to this inquiry and voiced his concerns.
I guess I am outvoted 21 to 0 on this one and yes, I knew about the expansion valve requirement and that I could add a branch off the main forced air system with a controlling damper, but my basement is about 10 degrees cooler than the upstairs single zone, so that I don't get heat to the basement room when there is no call or need for heat upstairs. Separate zoning won't work since the blower would flow only about 150CFM for the basement which is not enough for the main unit.
However, I am going to listen to you all and add the ducting and set the thermostat (to control the new damper) at about 8 degrees higher than requred temp to allow cooling down when I have the condition I described above. If that doesn't help, I will wait, as some of you have mentioned for my HWH to conk out ( its 14 years old anyway) to install a HWH with a separate heating coil and finally get what I wanted in the first place.
I deeply appreciate the wonderful people on this wonderful site who give their time and expertise to help DIYers like me.

zeke

Joe,
Yes , I will wait for my HWH to conk out (its 14 years old) or maybe push it to conk out.
Thanks for your input.

Richard_4

get yourself a bock water heater and jack the t-stat upto max, add a domestic tempering valve for the potable water. tee off the hw supply before the tempering valve to supply the heating loop and return into the bottom of the bock. dont forget to add a circulator,relay and room t-stat. 50gal bock should be enough. go on line to get the drawing from bock.

Joe Brix

Do some planning now

If a new furnace is in your near future also, think about a hydro air replacement. Boiler, indirect tank and an air handler with heating coil to replace your furnace (and AC?)
Combo water heaters are expensive and probably live only as long as a regular WH. You'll get better efficency and longer life with a boiler. It will cost more, so start saving your money now.

Cosmo_3

150 cfm no problem

Just need a static pressure bypass damper. Maybe a consult with a professional could save you money AND give you the comfort you need. Of course if you want real comfort you gotta get a little wet



Cosmo Valavanis

Dependable P.H.C. Inc.