Radiant Heat

Darko9000 · Nov 27, 2016

Hello everybody,

First I want to say thank you to this whole community. I was able to learn a lot to help me in building process of my workshop.
I have a shop area approximately 1400 ft.² that I'm looking to heat with radiant heat. I have built a 5 inch slab which is thermally separated from outside with a two inch Styrofoam insulation from the sides and the bottom. I have ran approximately 2000 feet of half-inch PEX. I have eight runs approximately between 250 in 300 feet long.
I am looking for some help to tie everything together. I drew a little sketch up of what I learned here at the forum how my system should possibly look on the wall, does that portion look okay?
I have also installed half-inch PEX going from my utility room to the middle of the slab, approximately 12 feet, so i'm planing to slide in a little concrete sensor.
So this is the part that I'm not quite sure.
I'm assuming the pump is going to be 110 and the thermostat is low-voltage, how do I tie in thermostat pump and a sensor together, what kind of a controller box or anything do I need? Size of my pump?

This is one zone only.

Help is greatly appreciated

Darko

Darko9000 · Nov 27, 2016

Forgot to mention that I'm going with instant hot water heater.
I called eco-smart and talk to their tech guy, he recommended eco-smart 18 for my size of the shop.
Since this is going to be a close loop, what kind of antifreeze should I use?

Thanks

theoldwizard1 · Nov 28, 2016

Think twice about using any kind of electric heat source. $$$$ !!

Firebrick43 · Nov 28, 2016

Are the fill valves actually purge valves? If not they will not work like that, at least not without an additional valve. I would put pressure Gage's where the fill valves are to see pump pressure/differential.

Your local electric company is going to have quite a bonus in the future!

Darko9000 · Nov 28, 2016

Thanks for your quick reply!

I was thinking a lot about should I do this with electric or not, I do have a gas available at my house but I have decided to go with the electric because I'm going to install solar panels on my roof in a year or two, price of solar panels has come down a LOT in the last couple years so hopefully my electrical company is going to love me for a first year or two

. Forgot to mention that my walls are two by six with a spray foam insulation so that should help.

I have updated my drawing, hopefully things look a little bit clearer now.

Firebrick43
I have now filled/purge valve in front of the pump, is that okay?

I have removed the pressure gauges by the electrical heater because the stainless steel manifold comes preinstalled with pressure and temperature gauges so I guess I shouldn't need those.

So this is what I'm not still clear on:

1.What thermostat should I use, this is going to be heat only?

2.What slab sensor should I use? When I was pouring the concrete i installed the piece of half-inch PEX pipe that goes to the middle of the slab so I can insert the sensor later.

3.Does the slab sensor connects to a thermostat or a taco switching relay?

Thanks for your help

Firebrick43 · Nov 28, 2016

You need two bib/drain to purge air. It just needs a valve between them so purge fluid doesn't take the short route but the long way around. A purge valve has a valve and bib/drain in one.

I would consider an outdoor reset instead of slab temp control. Slab temp is very slow to respond to load changes.

James-W · Nov 28, 2016

I know you won't want to hear this, but I would go with a natural gas fired boiler designed to be used with this type of heating system.

Darko9000 · Nov 28, 2016

Sorry if I seem slow but a lot of this stuff is new to me.

I am looking at Paxuniverse.com http://www.pexuniverse.com/webstone-pro-pal-48613-purge-and-fill-valve

is that what you're describing "3/4" NPT Threaded Purge & Fill Ball Valve w/ Hose Drains"
it comes with a valve between them.

Can you tell me more about the "outdoor reset", I was under impression that having a slab sensor is a little bit better then just having thermostat on the wall by itself but I wasn't aware of the "outdoor reset" that your mentioning

Darko9000 · Nov 28, 2016

James-W said:
I know you won't want to hear this, but I would go with a natural gas fired boiler designed to be used with this type of heating system.

I'm going to be using a lot of electricity there, different woodworking machines and a lots of welding.
I'm pretty lucky that my roofline is facing south and I'll be able to fill the whole's outside with solar panels. On the long run this is going to save me a TON of money. I'm actually hoping that in the next 5 to 7 years storage battery prices are going to be cheap enough to be able to completely disconnect from the electrical company.

Firebrick43 · Nov 29, 2016

Outdoor reset means the controller reads the outside temp, and some read the air and slab temp as well. It sees the outside falling in temp and it raises the temp of the floor before the floor even sees a drop due to the increased load. If the controller is set right it makes for a more even system.

You do realize the power and storage would cost north of of 60k if the price comes down significantly. The only way solar PV can come anywhere close is if it is driving a heat pump. Probably a geothermal.

kuhner · Nov 29, 2016

Don't let the non-electric boiler folks scare you off.
I have a 32 x 40 block garage, 4" of foam on the outside, good doors, and in central Ohio. I went with an electric boiler because I didn't want an open flame in a garage that may have flammable vapors, gasoline, paint thinner stuff like that. I am on AEP and not the cheapest rates, minimum monthly bill just for service is 45/month. Over the last 5-6 years my average bill is about 100. Average, those big 150/month winter bills hurt, but average it out its not too bad. I use a Seicor boiler.
I keep the temp at 60 and have a small water heater, and usually spend a couple hours a day after my real job up there.

rburke65 · Nov 29, 2016

kuhner.....what is your kW/h cost ? Going to do an electric boiler.Thanks. Now back to our regularly scheduled program.....

Darko9000 · Nov 29, 2016

The price of the electricity here in North Carolina is around 0.9 c kw

I have a six-inch of spray foam insulation and 2 inch of Styrofoam under the slab so i'm hoping it's not going to be too bad.

I have updated my final layout drawing, I would appreciate any input

coldh2o · Nov 29, 2016

You don't need that purge & fill valve, there are valves for that purpose on the manifold.

I would put a hose bib/boiler drain at the lowest part of your system so you can drain the piping if need be.

Ball valves either side of the pump so it can be removed without draining the system.

Darko9000 · Nov 29, 2016

coldh2o,

Thanks for your input, you are absolutely right purge and fill valves are on the manifold I don't know how I missed that.

I have updated my drawing with your suggestions

kuhner · Nov 29, 2016

I believe cost per Kwh is about .11
That's with all the taxes and fees tacked on.

tdkkart · Nov 29, 2016

kuhner said:
Don't let the non-electric boiler folks scare you off.
I have a 32 x 40 block garage, 4" of foam on the outside, good doors, and in central Ohio. I went with an electric boiler because I didn't want an open flame in a garage that may have flammable vapors, gasoline, paint thinner stuff like that. I am on AEP and not the cheapest rates, minimum monthly bill just for service is 45/month. Over the last 5-6 years my average bill is about 100. Average, those big 150/month winter bills hurt, but average it out its not too bad. I use a Seicor boiler.
I keep the temp at 60 and have a small water heater, and usually spend a couple hours a day after my real job up there.

rburke65 said:
kuhner.....what is your kW/h cost ? Going to do an electric boiler.Thanks. Now back to our regularly scheduled program.....

I'm in the same frame of mind, safety, convenience, price, and existing equip has forced my hand to using electric. My 30x40 shop's average monthly bill for the past 12 months has been $65. 8 months really low, 4 months of high bills each year. The electric is dead quiet, safe and reliable.
I've run the same electric on-demand heater for 7 years with not one single issue.

James-W · Nov 29, 2016

Nobody ever said that electric doesn't work, just the opposite, it works and works very well. It's just that the cost to use it is quite a bit more than using some of the other energy sources.

Darko9000 · Nov 29, 2016

Things guys for the info,

those electrical charges seems pretty reasonable, I love working with lacquer and having sawdust, lacquer and open flame in the same building terrifies me.

10 years ago my wife and I took a vacation to Banff Canada and this was the first time I experienced radiant heat, and I decided then that this is the only heat I will ever do in my house or workshop.

Any other input, or anything else I'm missing in my design?

Sokoloff · Nov 30, 2016

Darko9000 said:
The price of the electricity here in North Carolina is around 0.9 c kw

There's no place in the US with power under a penny per kWh. Your rate is probably 9 cents/kWh, not 0.9 cents.

I mention because a factor of 10 matters if you're basing "Ah, that won't be too bad" on a cost that's 1/10th of real.

theoldwizard1 · Nov 30, 2016

James-W said:
Nobody ever said that electric doesn't work, just the opposite, it works and works very well. It's just that the cost to use it is quite a bit more than using some of the other energy sources.

More like EVERY OTHER heat source !

Lots of insulation will help. Adding any amount of solar that can be sold back is a big win. This varies by location.

theoldwizard1 · Nov 30, 2016

Darko9000 said:
10 years ago my wife and I took a vacation to Banff Canada and this was the first time I experienced radiant heat, and I decided then that this is the only heat I will ever do in my house or workshop.

I can't argue with that !

If you don't mind, what do you estimate the cost of the all the plumbing and boiler to be ?

A friend of a friend was quoted >$40k on a new build of about 3200 sq ft. (Walk out basement and ground floor.) Seems very high to me.

Darko9000 · Nov 30, 2016

If I remember correctly 2000 feet of PEX tubing was about $500, the other miscellaneous little things like zip ties was another hundred bucks.
My friend let me use his copper manifolds to pressurize the system during concrete pouring
if you look in one of the earlier posts I have the list of all the things I'm going to order

ECO 18 | 18kW Electric Tankless Water Heater is around $360 on Amazon

Pretty much everything else is from pexuniverse around $750

If you include another $200 for 2-40 amp breakers and miscellaneous copper fittings

The total material price is roughly $2000

I used one of the free software for a month to do the piping layout, I cannot remember the name of it now. A friend of mine helped me lay down all the pipe and strap everything

This is a building 25 x 60 12 feet tall excluding utility room I am heating roughly 1400 ft.²,

Couple years ago we had one of those homes shows with a lots of businesses advertising their services so I called one of the companies and the price was over $10,000 I cannot remember what it was exactly.

mustangfan · Dec 1, 2016

Some people do not like Radiant heat for some reason or another. I am not sure if their system was designed correctly or what. I like the fact it can be -20 outside and if I want to walk around barefoot on the concrete, I can. In my workshop with hot air, you won't be waking around without shoes on because the concrete is always COLD>

In our house, we put the tubes under the floor in our kitchen. Our kitchen and Dining room both have crawl space under them. We do not have the radiant/in floor in the Dining room yet.
Last winter the temp in the kitchen at 6 feet up was 68', the temp in the dining room at 6 feet up was 66'.
BUT the floor temp of the kitchen was 75 and the floor temp of the dining room was 55'
Big difference when you heat the floor!!
Your setup looks good. You will also be able to get some FREE radiant from the windows!!
ENJOY

Darko9000 · Dec 2, 2016

Can anybody who has a similar size system tell me is this pump

UPS15-58FC 3-Speed Circulator Pump w/ IFC, 1/25 HP, 115V
http://www.pexuniverse.com/grundfos-ups15-58fc-circulator-pump-59896341

that I'm planning to use enough to circulate water through the whole system?

Should I possibly change this to a primary and secondary loop system or leave it like this?

Thanks

TheEquineFencer · Dec 3, 2016

What part of NC are you in?

Darko9000 · Dec 3, 2016

I am in Cary NC

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