# In floor radiant heat.



## FarmerDavid (Jul 16, 2012)

I am looking for advice in designing an in floor radiant system for our remodel. I would like to be able to use the same hot water heater as we will for normal use. I want at least three zones. The first is a mud room and bathroom, dimensions are approx 10x30. The second One is the remainder of the bottom floor, roughly 30x30'. The third is the upstairs. Approx 12x30'. After seeing it online while doing some research I'm also considering doing an interior wall one the first floor as another zone. Also the upstairs ceiling could be a possible zone. The last two zones really depend on how much expense they add. 

I know ill need seperate thermostats for each zone. Ill need defusers. Any chance I can get by without them on the second floor? All floors are wood with no subfloor. I don't really know what ill need as far as manifolds valves and pumps. This will be the main, if not only heat source for the house. 

Where are the best places to buy supplies? I've done most of my online looking at pexsupply.com. I've also looked at radiantech.com


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## haypoint (Oct 4, 2006)

Do you mean you will use the same style water heater as you use for your domestic hot water? You do not intend to circulate hot water from your household water heater to heat your house , do you?
I doubt you'd benefit much by a second floor radiant heated ceiling.


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## NorthwoodsMike (Jun 10, 2013)

FarmerDavid said:


> I am looking for advice in designing an in floor radiant system for our remodel. I would like to be able to use the same hot water heater as we will for normal use.


You are suggesting an OPEN system. While this is possible, I don't recommend it. With a tank type water heater, it doesn't have the output to provide both your hot water, and your heating system. When the weather is really cold, your in floor heat may never shut down-it's designed to just idle along. A properly sized on demand system could probably keep up, but if you have hard water, you will be dealing with scale buildup.

I firmly believe a closed system is the only way to go. This keeps your regular hot water separate, so there is no shortage. It also allows you to run a light mixture of antifreeze in the heat system, which helps lubricate. Even better, the water heater used on the heat system will have minimal hard water buildup. Once it "cooks" out any existing hardness, you are basically running distilled water.

What fuel to you plan to use to heat the water?



FarmerDavid said:


> I want at least three zones. The first is a mud room and bathroom, dimensions are approx 10x30. The second One is the remainder of the bottom floor, roughly 30x30'. The third is the upstairs. Approx 12x30'. After seeing it online while doing some research I'm also considering doing an interior wall one the first floor as another zone. Also the upstairs ceiling could be a possible zone. The last two zones really depend on how much expense they add.


Keep the zones in the floor, even if it means a little extra work. Drywall isn't a good conductor of heat, and you need that natural convection process to keep things an even temperature.



FarmerDavid said:


> I know ill need seperate thermostats for each zone. Ill need defusers. Any chance I can get by without them on the second floor? All floors are wood with no subfloor.


By defuser, do you mean transfer plate? You can, but typically you would need to run your water hotter, and it is less efficient. How thick are the floors? Knowing there is no subfloor, if you put transfer plates on the bottom of the boards, you would have one heck of an efficient system.



FarmerDavid said:


> I don't really know what ill need as far as manifolds valves and pumps. This will be the main, if not only heat source for the house.


There are a couple of options with pumps. I opted for a single pump, and zone valves, and have had great luck. Some setups have a pump for each zone, but if you have even headspace between the loops, that shouldn't be needed. You also don't need to have more than one thermostat. You could have manual zone valves, which could be adjusted to keep the heat even. That is what we have at our cabin. 



FarmerDavid said:


> Where are the best places to buy supplies? I've done most of my online looking at pexsupply.com. I've also looked at radiantech.com


I've used pex supply alot. I used Menards (there are some in MO) more, simply because I could return what I didn't use.

There is so much you can do with a system like this. You can go super basic, or super complicated. I have done both, so your budget definitely plays a role. Was there a dollar amount you had planned to stay around?


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## FarmerDavid (Jul 16, 2012)

haypoint said:


> I doubt you'd benefit much by a second floor radiant heated ceiling.


That was my original thought as well but the house we are currently in has in ceiling electric. My wife likes to turn it on in the bed room at night and it really does make a big difference. If it would work as good as that system does it would be nice. The people before us used it as their dole source of heat. They had a central heat and air system but didn't have gas hooked up for some unknown reason. The ceiling is low on the list just an idea.


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## FarmerDavid (Jul 16, 2012)

NorthwoodsMike said:


> There are a couple of options with pumps. I opted for a single pump, and zone valves, and have had great luck. Some setups have a pump for each zone, but if you have even headspace between the loops, that shouldn't be needed. You also don't need to have more than one thermostat. You could have manual zone valves, which could be adjusted to keep the heat even. That is what we have at our cabin.
> 
> 
> ?


Closed system it is then. I wasn't sure about keeping up with demand with an open system. 

Yes I meant transfer plate. 

Well heat the water heater with natural gas. Fortunate that the main has an easement across the road and we have a meter even out here. There is also three phase and fiber optic cable. 

Floors are 3/4" pine. 

No I don't have an exact $ figure. I should be able to do all of the work myself to keep labor costs down. I want to do it right and be happy with it. I'm a big believer in doing something right the first time and not having to do it again. That's both a good and bad trait, as I have several projects that need done around here but don't have the resources to do them how I want so I have nothing done on them. I don't know enough about the setup to know what the differences between a super basic and a super complicated system is. I have a manifold ill go dig it out of the barn and let you know what it is I'm hoping we can work with it.


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## NorthwoodsMike (Jun 10, 2013)

FarmerDavid said:


> Well heat the water heater with natural gas. Fortunate that the main has an easement across the road and we have a meter even out here. There is also three phase and fiber optic cable.


With this, you really have the option of going on-demand, or tank. I picked up my on demand water heater for $500 from Menards when they had a rebate sale going. In this application, I'm comfortable with O.D. for the reasons I listed above-the water becomes distilled. Use a tank for your regular system. How much is a NG regular water heater these days?



FarmerDavid said:


> Floors are 3/4" pine.


I'd definitely go with heat transfer plates then. They can be easily mounted using 1/2 in machine screws. The screws for the other style loops might be a bit too long.



FarmerDavid said:


> No I don't have an exact $ figure. I should be able to do all of the work myself to keep labor costs down. I want to do it right and be happy with it. I'm a big believer in doing something right the first time and not having to do it again. That's both a good and bad trait, as I have several projects that need done around here but don't have the resources to do them how I want so I have nothing done on them. I don't know enough about the setup to know what the differences between a super basic and a super complicated system is. I have a manifold ill go dig it out of the barn and let you know what it is I'm hoping we can work with it.


Features and automation. Having multiple thermostats is nice, but you need a more robust controller and more electric zone valves, not to mention additional t-stats and wiring. A pump feeding a manifold with manual balancing valves can be done much cheaper, and does the job.

Edit:On the budget note, the system could be built on the cheap now, but setup to add the extra/tstats later. 

Also, regarding a water heater, I'm rethinking recommending OD. That adds a second circulator "loop" to the mix, which also adds expense. I forgot about that part.


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## painterswife (Jun 7, 2004)

We have been running and open system for 12 years now and it works well. That said it sounds like you will need far more BTU's then you would get efficiently with a regular water heater so would be better off going with a boiler and a closed system. The right small boiler will do both domestic and radiant.


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## NorthwoodsMike (Jun 10, 2013)

painterswife said:


> We have been running and open system for 12 years now and it works well. That said it sounds like you will need far more BTU's then you would get efficiently with a regular water heater so would be better off going with a boiler and a closed system. The right small boiler will do both domestic and radiant.


Do you have hard water? Have you had issues with supply if it shares a water heater? What do you heat your water with?

I've never used an open system, so your first hand experience outweighs my theory


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## FarmerDavid (Jul 16, 2012)

This is what I have. Also have 600' of pex. Originally they were going to go in a garage that never got built.


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## painterswife (Jun 7, 2004)

NorthwoodsMike said:


> Do you have hard water? Have you had issues with supply if it shares a water heater? What do you heat your water with?
> 
> I've never used an open system, so your first hand experience outweighs my theory


We have hard water and must use a water softener. I have a propane on demand and an electric hot water tank both plumbed into the system. I use what ever is cheapest that year.

We have a small house with 2 inch concrete on a wood deck. Two zones. SIP walls. We can heat almost all the time with a 40 gallon electric water heater (unless the temp outside goes below zero for days on end) and still have enough domestic hot water for the two of us. We don't set back the heat but we have it programmed to go off for an hour or so in the morning when we might be taking showers.


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## NorthwoodsMike (Jun 10, 2013)

FarmerDavid said:


> This is what I have. Also have 600' of pex. Originally they were going to go in a garage that never got built.


Is there an inlet on that? What is with the hose clamp? Could it work? Yes, but if it were me, I would recycle the parts into other things on the system.

At a minimum, I would get something like this-it lets you turn the zones on/off:










This is better-as it allows you to balance the zones:

http://www.pexsupply.com/Sioux-Chief-672XB0342-1-Copper-Manifold-w-1-2-Crimp-Balancing-Valves-3-Outlets?gclid=COae1pePs7wCFecRMwodaEgAbg

This is best, as it allows for balancing while showing the flow, and zone valves can be seamlessly added later, but initially some special fittings are needed:

http://www.menards.com/main/heating-cooling/hydronic-radiant-heat/manifolds/ss-3-branch-hydronic-manifold/p-1713131-c-8520.htm


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## NorthwoodsMike (Jun 10, 2013)

painterswife said:


> We have hard water and must use a water softener. I have a propane on demand and an electric hot water tank both plumbed into the system. I use what ever is cheapest that year.
> 
> We have a small house with 2 inch concrete on a wood deck. Two zones. SIP walls. We can heat almost all the time with a 40 gallon electric water heater (unless the temp outside goes below zero for days on end) and still have enough domestic hot water for the two of us. We don't set back the heat but we have it programmed to go off for an hour or so in the morning when we might be taking showers.


Sounds like a good setup. Do you have to clean the OD water heater for scale ever? How many sq feet are you heating?

David, if you don't have terribly hard water, and had a softener, this would work very well as the OD heater would give you more than enough hot water. You would need a second circulator, but that could be a simple on/off switch. Edit(or an electric style water heater t-stat could also turn the circulator on and off)


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## painterswife (Jun 7, 2004)

We heat 1200 square feet and yes the on demand needs scaling once in a while. Less now that we have a softener in.


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## NorthwoodsMike (Jun 10, 2013)

painterswife said:


> We heat 1200 square feet and yes the on demand needs scaling once in a while. Less now that we have a softener in.


The more I hear, the more I wish I could have done a setup like this. My issue is I have a new well, and the water is crazy hard, and a softener can only do so much. I suppose I could have used a heat exchanger and kept the OD water heater on it's own closed loop.

Ah well-shoulda woulda coulda


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## painterswife (Jun 7, 2004)

NorthwoodsMike said:


> The more I hear, the more I wish I could have done a setup like this. My issue is I have a new well, and the water is crazy hard, and a softener can only do so much. I suppose I could have used a heat exchanger and kept the OD water heater on it's own closed loop.
> 
> Ah well-shoulda woulda coulda


Our water is crazy hard as well. The nice thing about my system is it is simple and I can use the cheapest fuel.


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## FarmerDavid (Jul 16, 2012)

You know I don't know what the hose clamp is for or the inlet. I hadn't seen it in 5 years before I took that pic and it really wasn't what remembered it. 

How many ft of line can you put in a run? The biggest zone would be roughly 700' if it was on one run that seems kind of long to me. Two runs in that zone?


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## NorthwoodsMike (Jun 10, 2013)

FarmerDavid said:


> You know I don't know what the hose clamp is for or the inlet. I hadn't seen it in 5 years before I took that pic and it really wasn't what remembered it.
> 
> How many ft of line can you put in a run? The biggest zone would be roughly 700' if it was on one run that seems kind of long to me. Two runs in that zone?


I think 300' is permitted, but I would never go that far. 250' max. I'd go for 3 in that zone, if not 4.


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## FarmerDavid (Jul 16, 2012)

Lets just say 4 rather over do it. Is that manifold that you posted from menards then hooked into a seperate manifold for runs within the zone?


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## NorthwoodsMike (Jun 10, 2013)

Exactly. No shutoffs required.


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## FarmerDavid (Jul 16, 2012)

Been looking at pex supply some more tonight. If I'm reading stuff right an open system needs pex with an o2 barrier and stainless pumps. I guess everything in the domestic water supply would need to have an o2 barrier as well? I don't know about efficiency but the higher costs of the o2 barrier equipment negates any savings I was hoping to acheive by not buying a second heater. Looking at some pdf's on the radiantec web site I think I could do an open system and be fine with demand. So I'm still kind of debating open v closed system.


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## NorthwoodsMike (Jun 10, 2013)

FarmerDavid said:


> Been looking at pex supply some more tonight. If I'm reading stuff right an open system needs pex with an o2 barrier and stainless pumps. I guess everything in the domestic water supply would need to have an o2 barrier as well? I don't know about efficiency but the higher costs of the o2 barrier equipment negates any savings I was hoping to acheive by not buying a second heater. Looking at some pdf's on the radiantec web site I think I could do an open system and be fine with demand. So I'm still kind of debating open v closed system.


Edit:

http://www.pexsupply.com/resources/radiantHeat

I deleted my previous comment as it was confusing. OK, so here is the deal:

Closeds system require barrier pex, and it allows you to use cast iron pumps since oxygen is kept away from them.

Open systems do not require barrier pex, but the pex has to be approved for drinking water, and because oxygen can exist in the system, stainless steel pumps must be used.

Ideally, if you can find a potable water approved barrier pex, that is best, because you can switch to a closed system later.

Can you use a non-potable water pex in an open system? The consensus is that yes, you can, as manufacturers note that there is no difference between it and potable water pex, other than a special coating on the outside. It's extremely expensive to get the certification on it, which is why it must be labeled non-potable. You may not have an issue with it, but an inspector might, or a future home buyer.

David, since you have a big roll of pex, I would just stick with an open system, using non-barrier.


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## NorthwoodsMike (Jun 10, 2013)

painterswife-have you run into bacteria in your water at all, primarily in summer when the lines are stagnant?


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## painterswife (Jun 7, 2004)

NorthwoodsMike said:


> painterswife-have you run into bacteria in your water at all, primarily in summer when the lines are stagnant?


No, I run cold water through the floor and to outside during the summer or I shut the floor off from the domestic for the summer. I plumbed my system myself so can change it when ever I want.


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## NorthwoodsMike (Jun 10, 2013)

painterswife said:


> No, I run cold water through the floor and to outside during the summer or I shut the floor off from the domestic for the summer. I plumbed my system myself so can change it when ever I want.


Interesting way to get around the bacteria issue. 

I assume you have two circulators, right? I'm curious how you have them plumbed. Are you willing to share pictures?


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## painterswife (Jun 7, 2004)

NorthwoodsMike said:


> Interesting way to get around the bacteria issue.
> 
> I assume you have two circulators, right? I'm curious how you have them plumbed. Are you willing to share pictures?


No pictures. It is all in the crawl space and I can.t go there at the moment due to a broken limb.

Two zones. One pump per zone. Two three hundred foot pex circuits per zone. Very simple system.


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## NorthwoodsMike (Jun 10, 2013)

painterswife said:


> No pictures. It is all in the crawl space and I can.t go there at the moment due to a broken limb.
> 
> Two zones. One pump per zone. Two three hundred foot pex circuits per zone. Very simple system.


So there isn't a circulator between the electric and on demand? Interesting.

So does water enter the electric tank, go through it, then into the od system, where it splits and goes to potable on way, and toward the in floor heat another way. Eventually going through tubing and circulators before returning to the electric tank?

I'm just trying to picture the plumbing. For whatever reason I thought you were constantly circulating hot water through the side arm of your tank unit, and house/heat came from there.

Thanks for answering all of the questions. As I said earlier, I've only done closed loop.


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## painterswife (Jun 7, 2004)

NorthwoodsMike said:


> So there isn't a circulator between the electric and on demand? Interesting.
> 
> So does water enter the electric tank, go through it, then into the od system, where it splits and goes to potable on way, and toward the in floor heat another way. Eventually going through tubing and circulators before returning to the electric tank?
> 
> ...


Water plumbed to both heaters, then goes to out splits to either heat or DHW. After it leaves heat zones it goes back to the heater being used. The returning water can be run through the on demand or the electric or both( on demand first).


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## NorthwoodsMike (Jun 10, 2013)

I see. So you use ball valves to control the flow. Interesting.


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## FarmerDavid (Jul 16, 2012)

painterswife said:


> No, I run cold water through the floor and to outside during the summer or I shut the floor off from the domestic for the summer. I plumbed my system myself so can change it when ever I want.


This is what confused me on the o2 barrier in an ppen system. In the diagram I'm looking at when the heat isn't being used its being circulated back through to be used on the domestic side so it shouldn't be stagnant even in the summer months or I can install ball valves so it drained when not in use so I don't understand why the pex needs to be different. In a closed system where the same water is constantly recirculated I understand. The stainless pumps are a bigger expense in a open system but if you can use the normal pex it isn't as bad. 

I've had a busy couple of days and haven't got to study this much more I'm hoping to be able to look into it and maybe come up with a diagram in the next few days.


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## FarmerDavid (Jul 16, 2012)

I'd also say there is no code out here. I don't plan to ever sell the place so my primary concern is the safety of
The drinking water if we do an open system.


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## painterswife (Jun 7, 2004)

FarmerDavid said:


> This is what confused me on the o2 barrier in an ppen system. In the diagram I'm looking at when the heat isn't being used its being circulated back through to be used on the domestic side so it shouldn't be stagnant even in the summer months or I can install ball valves so it drained when not in use so I don't understand why the pex needs to be different. In a closed system where the same water is constantly recirculated I understand. The stainless pumps are a bigger expense in a open system but if you can use the normal pex it isn't as bad.
> 
> I've had a busy couple of days and haven't got to study this much more I'm hoping to be able to look into it and maybe come up with a diagram in the next few days.


The water in the floor loops in mine one move if the thermostat calls for heat and turns on the pump. So I either have two choices. Either I change the flow in the summer and have the water go through the floor first before it hits the heater or I have the water flow through the floor on its way to an outside tap.


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## FarmerDavid (Jul 16, 2012)

painterswife said:


> The water in the floor loops in mine one move if the thermostat calls for heat and turns on the pump. So I either have two choices. Either I change the flow in the summer and have the water go through the floor first before it hits the heater or I have the water flow through the floor on its way to an outside tap.


So if it goes through the floor first doesn't the tubing in the floor in essence become just an extension of the supply line?


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## painterswife (Jun 7, 2004)

FarmerDavid said:


> So if it goes through the floor first doesn't the tubing in the floor in essence become just an ejust become an extension of the supply line?


Yes, it does.


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## FarmerDavid (Jul 16, 2012)

Looks like this project is going on the back burner. A plumbing issue has arisen and rather then just patch it Ill be replumping the entire house since I'd planned on it anyway. Planned on doing that later since it was functional but since its no longer functional its getting priority. So thats taking my time and money. 

It's also getting warmer and ill have lots of outdoor jobs that its time to get to. im bookmarking this thread as I'm sure ill have more questions when I get back to this project, probably in the middle of summer when heat is the last thing on anyone's mind.


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## NorthwoodsMike (Jun 10, 2013)

Sorry to hear that. Are you going to use pex? That roll you have in the barn would be perfect.


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## Morris (Jul 16, 2014)

Hi everyone

I just bought 10 acres with an Amish built Agri pole barn built on it in 2012.
It was completely open and sand floor.
.
I graded the inside and packed the sand base, put down 2" XPS foam in 1" boards, duct taped the seams and put a 2nd layer of 1" foam crosswise so no seam goes thru. 
Then 5"x5"x60" steel fencing was laid down, PEX O2 tubing wire tied to the fencing in 10" loops, all in floor connections I used brass PEX connectors covered with heavy weight shrink tubing, then PEX, true 4"+ cement on top.
The 3 main areas of the shop floor are isolated from each other by a 2"x8" and 24" perimeter rat wall with 1" XPS foam isolating the rat wall from the slabs.
All PEX zones 300-388ft long.
3 zones in the 14&#8217; x 56&#8217; man cave area. 7 zones in the 30&#8217; x 56&#8217; workshop area. 3 zones in the 14&#8217; x 56&#8217; garage area.
.
New insulated 14'x16' doors and 3 36" pedestrian doors.

The shed is currently not insulated; It will eventually be foamed in leaving an 1-1/2" dead air space between the steel and the flat 3/8" foam board that will be stapled to the 2"X4" battens every 24" up the wall. The spray foam will be sprayed to the foam board 3-1/2" thick on the walls then covered with OSB board and 5" thick foam at the inner roof trusses.
.
I want the glycol closed system using solar collectors and LP gas backup somehow.
I just want to heat the cement to 50Âº, when I move up there permanently I want 65Âº after the spray foam is installed.
What solar collectors/pumps/valves/etc do I use?
Also need to heat some water for a shower/vanity, so I'm thinking a 250 gallon poly water tank with the aluminum frame (insulated to save heat) as a storage reservoir and a place to put a 100ft coil inside the tank to heat my domestic water.
.

That's all I have done.....
Can anyone help me with a parts list of what I need to buy to finish this up.

thanks for any advice....ed


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## NorthwoodsMike (Jun 10, 2013)

I can't speak to the solar collection, but plumbing in a simple water heater immediately before it goes into the floor would give you your propane backup. If the solar doesn't produce, it will kick in. You may want a valve and secondary pump system. The solar loop would kick in only if the panels achieved a certain temp. I may be wrong, but I don't know that a large water tank would store enough thermal mass to be worth it. Again, I may be wrong on that. Depends on how many gpm you are moving and what your delta T is. It could be that the solar raises the temp halfway, and the propane does the rest.

Apologies if I sound "disjointed"-summer is short in the MI Upper Peninsula, so margaritas are enjoyed when possible.


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