Floor heat question

[washman2016]

I have a 20 year old heater for my floor heat that should be replaced. I had this idea, what if I run copper tube through my hot water storage tank and heat the coolant that way. Would I save money in the long run?

Rick

 

[2Biz]

You would only save money if your hot water boiler has a higher efficiency rating than the old floor heat boiler.

 

[soapy]

I have a couple of Voyager hot water tanks that come with copper tubes installed in the tank for this purpose. I have never used them for this as I have dedicated boilers for the floor heat. It would be possible to do what you are doing but you would probably need a long coil of copper in the tank to maximize exposure to absorb the heat.

 

[WikiWash]

Im not familiar with your setup but it almost sounds like you may be interested in checking out a heat exchanger.

 

[Rudy]

Doubtful you could get enough heat transfer for it to work.....

 

[WikiWash]

Doubtful you could get enough heat transfer for it to work.....

It all depends on the setup. I think we all know a heat exchanger can't take place of a boiler. A heat exchanger can make your system run more efficiently.

I just installed a brand new 400K btu triangle tube condensing boiler for our floor heat. It works extremely well and very efficient. I have noticed a decrease in our propane bill. It is very energy efficient, on our old boiler you would burn your hand on the smoke pipe. Now with the new boiler its vented with PVC pipe and is warm to the touch. If pvc was used on our old boiler it would melt.

 

[2Biz]

A heat exchanger or copper tubing will work fine as long as it has enough capacity to transfer the amount of btu's needed to keep the floors ice free. Basically that's what a boiler is...Its a heat exchanger....The OP is wanting to do away with his old floor heat boiler and transfer the source heat to his water heater/boiler. The only way this will save him money is IF the water heater/Boiler has a higher efficiency rating than the old floor heat boiler. And yes, a condensing boiler has one of the highest ratings of any boiler on the market and is the cheapest to operate. So if he has a condensing water heater/boiler, odds are this will save him a lot of money in the long run. If the efficiency ratings of the 2 heaters are similar, there is no way making the change will save money. Its all about how to get as many BTU's of heat into the media/water/glycol compared to how many BTU's go up the chimney...

If you would like an alternative method using a "Much Cheaper" high efficiency condensing demand heater, check this thread out. Lots of valuable information about floor heat there. Stats of the worst month with this system are detailed on post 126 for comparison. I don't micro manage my floor heat any more since it is so reasonable to operate. Floors ice free even down to -15° tested.

http://www.autocareforum.com/showth...-Water-Heater-For-Floor-Heat&highlight=heater

 

[wash4me]

I have a 250,000 BTU Triangle Tube boiler with two Heat Exchanger's there 5 x 12 100 plate that I bought off of eBay. One of them does my hot water and the other one does my floor heat.
All you need is one of these heat exchangers and a small pump to pump the water through the Heat Exchanger instead of trying to put a coil in the tank. Ideally you would have two small pumps on a primary secondary system. Heat Exchanger was about $400 if I remember right the pump will be about 200 and that's about it. You would still need an air outdoor air thermostat and hopefully a slab stat to turn the pump off and on. I guess you would also need a freeze protection thermostat because theoretically you could freeze the water and ruin your heat exchanger. I would say this would save a substantial amount of money even if you don't have a super efficient hot water heating system because there are a lot of losses just from running a second system. How many BTU is your hot water system?

 

[2Biz]

If using a Primary/Secondary system like mine and using the heat exchanger instead of the Demand Heater, You'd have one pump that circulates glycol to the different zones. It could fire off the secondary output from the weepmiser at 32°. Then you could have an aquastat on the return glycol so that it would cycle the heat exchanger pump. No need for a slab stat. You may get by with one heat exchanger pump depending on the head pressure of the exchanger. My demand heater takes (2) Taco 013's to supply enough pressure to get enough glycol through the demand heater. Still a cheap alternative as long as the hot water heater/boiler has the capacity and is more efficient than the old floor heat boiler. In the heating world, you can't take out more than you put in!

You would also need a pump to circulate hot water from the boiler or holding tank. It could also fire off the return glycol aquastat.

 

[2Biz]

I guess the only problem I see going the heat exchanger route, is why not add $600 and get the super high efficient demand heater? You will pay for the heater in just a few months with the savings on NG…

http://www.supplyhouse.com/Takagi-T...ss-High-Efficiency-Condensing-Water-Heater-NG

 

[mjwalsh]

I have a 20 year old heater for my floor heat that should be replaced. I had this idea, what if I run copper tube through my hot water storage tank and heat the coolant that way. Would I save money in the long run?

Rick

Rick,

2 Biz's advice is good. Here is something that seems closer to what you are asking. Our use of two of the following: http://www.spirec.com/features.htm has been successful now since about 1990. In your case you probably would only need one. If you go the inline external heat exchanger route ... you may need help to size a specific pump that forces the heating fluid through the pass through heat exchanger at the rate that you need.

mike walsh www.kingkoin.com

 

[washman2016]

Thanks for the GREAT advise everyone. My hot water heater is only a few yes old and does a fantastic job. My thinking was I would still have to have a heater for the floor but maybe I could cut some cost in the size of the heater. As it is now I only run the floor heat during the day due to the cost of gas it wast. I will work the number and see what is best.

Thank you again for the ideas. You all have made being a new owner much easier.

 

[wash4me]

I guess the only problem I see going the heat exchanger route, is why not add $600 and get the super high efficient demand heater? You will pay for the heater in just a few months with the savings on NG…

http://www.supplyhouse.com/Takagi-T...ss-High-Efficiency-Condensing-Water-Heater-NG

I believe most of the savings are from the control system (thermostats on slab or return and outside air and lowering the temperature of the antifreeze going out) and also by not having 2 boilers running. He could install your system by reviewing your thread except with the heat exchanger instead of the demand heater and then if he decided in the future to get a demand heater all that would be left is to buy and hook up the demand heater. Also instead of buying a demand heater he could just do the same thing with a plain old commercial hot water heater. (there is just no need for the boiler circulation tank setup that is typical. He would also want another stat to make sure that the floor heat didn't overload and get the hot water below a certain temperature. It would just shut off the exchanger pumps until it recovered.

 

[wash4me]

Thanks for the GREAT advise everyone. My hot water heater is only a few yes old and does a fantastic job. My thinking was I would still have to have a heater for the floor but maybe I could cut some cost in the size of the heater. As it is now I only run the floor heat during the day due to the cost of gas it wast. I will work the number and see what is best.

Thank you again for the ideas. You all have made being a new owner much easier.

how many btu is your water heater? Is it a boiler and storage tank or just a large hot water heater?

 

[wash4me]

It all depends on the setup. I think we all know a heat exchanger can't take place of a boiler. A heat exchanger can make your system run more efficiently.

I just installed a brand new 400K btu triangle tube condensing boiler for our floor heat. It works extremely well and very efficient. I have noticed a decrease in our propane bill. It is very energy efficient, on our old boiler you would burn your hand on the smoke pipe. Now with the new boiler its vented with PVC pipe and is warm to the touch. If pvc was used on our old boiler it would melt.

Just wanted to make sure you were aware that the condensing efficiency only comes at lower temperatures. My boiler is currently putting out 96 degree water then through a primary secondary system (mixes the antifreeze from the boiler with antifreeze going out to the floor heat) that temperature is 79 degrees going out to the floor and 66 degrees coming back right now. This is warmer than necessary because below 0 the floors still don't freeze. You will gain about 20% gs savings using water below the condensing temp which is 120 I am thinking.
I have run the boiler at 64 or whatever the minimum setting is when it's just 25 outside.

 

[mjwalsh]

Thanks for the GREAT advise everyone. My hot water heater is only a few yes old and does a fantastic job. My thinking was I would still have to have a heater for the floor but maybe I could cut some cost in the size of the heater. As it is now I only run the floor heat during the day due to the cost of gas it wast. I will work the number and see what is best.

Thank you again for the ideas. You all have made being a new owner much easier.

Washman2016 & others,

Something tells me you are on the right track in terms of not needing both too much at the same time of the day or night etc. Floor heat does retain its heat for a long time we notice so absolute continuous duty for it does not seem that critical.

We have found that our water heating need is much less when the floor heat is needed more due to much lower outside temperatures etc. That is how & why the external Stainless Steel Spirec Heat Exchangers & the controls needed have earned their keep since about 1991. Our modular boiler system is one of the first renditions of 92% plus efficiency condensing units. The boiler water also goes thru our very own stainless steel versions of Amtrol HotWater Makers (improved from before) .

mike walsh www.kingkoin.com

 

[TheTallGuy]

Thanks for all your knowledge. This forum has been a great help to me since purchasing a 4 bay SS in Lincoln, NE. I have a CGM6 series 8 Weil-Mclain boiler for my floor heat. It has a temp control dial and a manual hi temp switch and that's about it. The hi temp switch bulb is zip tied on the output side? manifold under a piece of insulation(the hot side). And it has an air stat that turns it on and off. During cold spells the boiler runs non-stop until the temp gets above the setting on the airstat. No cycling on and off. Also, the circulator runs only when the boiler is firing. When the boiler does shut off, then the circulator shuts off. That's the way it came. Now, after reading all the past forums and blogs, I would like to make my system like you have. I just need alittle guidance. What kind of thermostat do I use to monitor the input side?(cool side) to turn the boiler on and off? How do I wire the output 2 on my weep mizer to turn the circulator on and off. Thanks. Any help is appreciated.

 

[Rudy]

My setup uses two Honeywell T675A 1516 thermostats. They sense from 0F to 100F.

If you are going to use the Weepmizer, you'd only need one. (My other one is used to sense the OAT)

The Weepmizer Output two should be wired to a relay to energize the circulator at about 34 degrees outside air temperature.

The Honeywell "stat" sensing bulb could be zip tied to the RETURN line of your floor heat....and insulated around the outside. The wiring of this stat would need to be connected to the "firing" control of your boiler. On my setup, when the return temp is below 75 degrees, the stat calls for "firing" (Heat). This is the adjustment which will need to be moved until you find what return temperature keeps your floors ice free.

Your present boiler control will have a wire that controls the "firing". It'd be up to you to find where this is.....or else call in an HVAC man

 

[mjwalsh]

My setup uses two Honeywell T675A 1516 thermostats. They sense from 0F to 100F.

If you are going to use the Weepmizer, you'd only need one. (My other one is used to sense the OAT)

The Weepmizer Output two should be wired to a relay to energize the circulator at about 34 degrees outside air temperature.

The Honeywell "stat" sensing bulb could be zip tied to the RETURN line of your floor heat....and insulated around the outside. The wiring of this stat would need to be connected to the "firing" control of your boiler. On my setup, when the return temp is below 75 degrees, the stat calls for "firing" (Heat). This is the adjustment which will need to be moved until you find what return temperature keeps your floors ice free.

Your present boiler control will have a wire that controls the "firing". It'd be up to you to find where this is.....or else call in an HVAC man

Rudy,

To add to your sensor on the pipe solution ... a service guy gave me some conductive paste to also put between the pipe & the sensor. Not sure how much it helps but he recommended doing that.

 

[Rudy]

You can use commonly available CPU heat sink paste. Also....I've been told that Anti-Seize also works. The Stainless Steel type of anti-seize is best (Has nickel in it). You do have that around your wash don't you? If you don't, take it from me....you want some. I've ruined more check valves and stainless fittings by not having them coated with anti seize. They often gall when tightening/loosening if you don't. Trust me.