Radient Floor Build with Qs

[xyster101]

After searching around the internet for days I have not really found a good radiant floor build. I figured I would share my setup here to help others and I will take any advice/criticism as I have never done a heating system. I am very handy, have sweat copper in the past, love PEX, and can't afford Sharkbites (just kidding).



I installed 2" foam under the slab and 1" foam around the perimeter. Then put wire mesh down and zip tied the Oxygen barrier pex to it. I got the 1/2" PEX from Amazon for $500 for 1,000 ft 5 years ago. I did 4 loops of ~250ft each so they are all the same resistance.



Pouring the concrete over the pex. Not sure why, but we did the front of the shop first and then the back a few days later.




Here is my CAD drawing. I am doing domestic HW for the sink and a hose spigot and the floor at the same time. This is an open system and I will not be drinking the water as the floor might get a little stagnant. Since I am taking water out for domestic, it should add a few gallons of water a week.

The circulator pump, air bleed, and expansion tank are on the hot side. This is called "pumping away" and is supposed to be a better way to set up the pump. I am using a Takagi T-KJr2-IN-LP tankless water heater from Amazon for $480 at 149,000 BTus.

I am running 3/4" LP black pipe to it.
All pipe is 3/4" also and I bought the flush valves from Amazon so I can run vinegar through it yearly.


Here she is getting plumbed in. The vent stack (not installed) has a condensation drain and also allows the cold air in for combustion. I did not want to use my warm shop air to burn the flame and shoot it outside.




$700 worth of plumbing fittings which I will return 1/3 of them. I live a good 30 min from HD so I buy extra. I think the local plumbing supply is cheaper but you can't wander around looking for things.

 

[Firebrick43]

It appears from your schematic that it will be an open system. I highly suggest you do NOT to an open system. Not only is it a possible breeding ground for really nasty diseases introduced into the DHW but it constantly is bringing in oxygen and minerals and therefore causing corrosion of valves/pumps/heater and scaling of the heater.

ALso you have no control of heat to the floor loops. You have a thermostatic valve on the DHW but the floor should never be above 100 degrees and you have full heat going to it.

 

[Radix2]

There are better ways to get domestic hot water than exposing your expensive stuff to minerals and oxygen - are you buying a stainless circulator ?

 

[xyster101]

I looked into a Rheem boiler that had 2 SS heater coils and would do DHW and radiant in separate coils, but that was $1800 for the unit, this was $500 (copper coil). If this unit dies in 5 or 6 years, that is still 1/3 the cost of a new proper unit.
You can adjust the temp of the hot water heater and I was going to set it at 100 degrees. Then turn it up if I needed hotter water on a garden hose.
I have a check valve from the domestic water supply to keep the water out of the drinking water. Is that not enough to keep the heat water out of the Domestic water?

 

[xyster101]

There are better ways to get domestic hot water than exposing your expensive stuff to minerals and oxygen - are you buying a stainless circulator ?

This was a schematic that was in the manual for the heater to get DHW and heat from one unit. I understand it will rot things faster and am prepared for that as I don't plan on using much hot water.
What would your solution be for both? Thanks for your input.

 

[kj_mustang]

Separate zone for the floor heat with its own pump and use a plate heat exchanger for the heat source. Keeps the floor heat as a closed system that you can add a water conditioner to and stays at proper pressure and the DHW side can stay open.

 

[xyster101]

Met with the propane company on where the two 100 gallon tanks will go. They were going to be too close to the exhaust so I moved the whole set up 90 degrees to the left. I had to change a few fittings.



A lot of the setups I have seen have the expansion tank just hanging out like this, but I don't like it. Are these usually support and if so how?

 

[Jackfre]

I suggest you do not skip over the comments on bacterial growth possibility. Typically, in an open system you have a control which will operate the heating circ daily even in the summer to prevent stagnant water in the system. You need that type of control.

 

[Highbeam]

If it was a real open system then you wouldn't need an expansion tank, your system is a hybrid.

Find a better way to heat your domestic water. I use a silly little 5 gallon resistance electric water heater under the sink. Not enough for many garden hose tasks but plenty to wash things.

 

[Radix2]

This was a schematic that was in the manual for the heater to get DHW and heat from one unit. I understand it will rot things faster and am prepared for that as I don't plan on using much hot water.
What would your solution be for both? Thanks for your input.

Cheapest would be a stand alone water heater, gas or electric. More expensive would be to run a tank with a hydro coil init.

If your use is limited, the under sink POU tanks cant be beat. Simple and cheap.

 

[jeepwm69]

I have a 40 gal water heater plumbed into with a small circulation pump. Closed system, last water heaters lasted about 40 years, and works great now that I finally got the air bled out of the system.

https://www.hondaatvforums.net/forums/around-garage/125144-hot-water-ciculation-system-heating.html

 

[EricVonHa]

Met with the propane company on where the two 100 gallon tanks will go. They were going to be too close to the exhaust so I moved the whole set up 90 degrees to the left. I had to change a few fittings.



A lot of the setups I have seen have the expansion tank just hanging out like this, but I don't like it. Are these usually support and if so how?

Here's how we supported mine with a bit of creative uni-strut placement and some all-thread hanger pipe clamps. This is installed directly adjacent to the boiler so it is very tough to accidentally hit it.

 

[xyster101]

I currently have a 30 amp/220v electric water heater under the utility sink that raises the water about 40 degrees which in the summer is fine, but the water only hits about 80 in the winter at the sink (water is actually turned off right now in the shop).
After all the advice, I will not use this for domestic.
I will also be looking at a timer to run the circulator pump for a pre set time over the summer. Any recommendations for such a timer control unit?



The white pipe was going to do to domestic. I will just cap it or put a garden spigot on the end for hose usage.

 

[Firebrick43]

Met with the propane company on where the two 100 gallon tanks will go. They were going to be too close to the exhaust so I moved the whole set up 90 degrees to the left. I had to change a few fittings.



A lot of the setups I have seen have the expansion tank just hanging out like this, but I don't like it. Are these usually support and if so how?

Hydro claw, about 30$. I bought mine from supplyhouse.com
View media item 89781

 

[Radix2]

I currently have a 30 amp/220v electric water heater under the utility sink that raises the water about 40 degrees which in the summer is fine, but the water only hits about 80 in the winter at the sink (water is actually turned off right now in the shop).
After all the advice, I will not use this for domestic.
I will also be looking at a timer to run the circulator pump for a pre set time over the summer. Any recommendations for such a timer control unit?



The white pipe was going to do to domestic. I will just cap it or put a garden spigot on the end for hose usage.

If you are switching to a closed system, there is no need to run the circulator over the summer.

The under sink tank types are a better fit for cold water areas. A little 5 gal one has plenty of hot water for any sink use, and gives piping hot water on a regular 120v circuit.

 

[xyster101]

Question: I am on a well which runs from 35-55 psi. What would a disadvantage be of running that high of a water pressure in the heating system?



Been working hard. Cut a 6 inch hole through the wall and ran the vent pipe which also doubles as the intake. Little scary cutting a big hole in my wall.



Ran all the 3/4" gas pipe. I have never worked with this pipe before. I pressurized from where the tank would be up the valve with 40psi. No leaks. I can't pressurized the heater with more then 1/2 psi to check for leaks. So I will when the gas man comes on Wednesday to do that.



You all on here said to secure the tank. So a wood block, metal strap and old bike tube looks good and works.



The piping coming out of the heater with clean out valves.



A shot from across the shop. It is a mess from all the work I have been doing. This stuff looks simple but sure takes long time to plumb and fit together!

 

[xyster101]

So I filled and bled the system. I did not fill the floor as I have a 5 ft loop above the floor to test the heater with before I put water in the floor. This way if the heater does not work I don't have to worry about the floor freezing.
With a valve located super high, bleeding seemed easy.

Question: How do I know I got all the air out?



You can see the garden hose going to the sink for bleeding. I also put in the condensation drain and attached everything to the wall.



Took a few minutes to sweep the shop and clean up everything.

 

[homebuilt burner]

You know the air is out when the pressure stays the same without adding water. On my system I could hear the air coming out of the air vent/eliminator. When I quit hearing the air coming out the pressure stabilized.

 

[xyster101]

I installed a pressure regulator and set it to 15 psi. I hope that is ok.



Gas guy showed up and dropped off two 100 gallon tanks. They are at 15% but will be filled tomorrow.



Vent pipe with exhaust and intake in the same unit. It heats the air coming in from the exhaust going out.



Borrowed an infrared camera and shot this once it was fired up for the first time.



Here is the floor after about 2 hours running. The floor started at 40 degrees. It is really neat how you can see the loops and see them getting colder. The hotter part of the loops are 48 degrees. Now 3 hours later the floor is 60 in some spots. Predator style!

 

[Vicious_Cycle]

Cool pics!
If you hear it gurgling, you probably have air in the system.

 

[xyster101]

The system has been running great for a few weeks. Took a bit to get the thermostat set properly because of the lag between when then T-stat says warm enough and the floor cools off.

A huge bonus is that snow covered stuff melts off quickly and the floor dries in a few hours!

Also made a video about what I did, how I did it, and what others should do:

 

[EricVonHa]

I installed a pressure regulator and set it to 15 psi. I hope that is ok.



Gas guy showed up and dropped off two 100 gallon tanks. They are at 15% but will be filled tomorrow.



Vent pipe with exhaust and intake in the same unit. It heats the air coming in from the exhaust going out.



Borrowed an infrared camera and shot this once it was fired up for the first time.



Here is the floor after about 2 hours running. The floor started at 40 degrees. It is really neat how you can see the loops and see them getting colder. The hotter part of the loops are 48 degrees. Now 3 hours later the floor is 60 in some spots. Predator style!

Was it a Flir camera that you used?

I'll need to do something similar in my garage mahal to track where my radiant lines are located. Planning on adding a 4 post multi-car lift in a section of the garage of which I did not take good radiant tube location photos when constructing.