Floor heat temp settings?

[SHINEY2]

Based on a very cold climate [north dakota] that stays frozen for months...what should I set my slab stat and return stat at?

Currently my slab is set at 38 degrees and my return is set at 70 degrees, my pump is running but my boiler has not turned on yet. Obviouly the concrete is warmer than the 38 degrees.
Should I change any of this?

Will these settings keep my bays warm and prevent freezeup?

Thanks for your help.

 

[Bubbles Galore]

I am in a similar situation but I won't be able to utilize a slabstat, I will have to reference the outside air.

SPA - Are you guys already seeing temps that mandate you turn your floor heat on??? I am usually good until Mid-December.

 

[Whale of a Wash]

There are too many variables to say if that will keep the bays warm. I think it may be too cool. In the middle of winter my concrete is probably close to 100 degrees or warmer to heat the bays. I have a Good indoor outdoor thermometer with a remote sensor. I put the remote sensor out in the bays in a plastic baggy,to keep dry. This way i know what the temps are out in the bays. I think if the weather is up and down alot the slabstat may fall short. If it is cold and windy and the bay doors are up and down alot the slab may be at the right temp and still cold in the bays. I just have in and out stats on boiler and for alot of the winter am at 140-160 out--hence the warm concrete. It would never melt ice at 38.

 

[SHINEY2]

I am in a similar situation but I won't be able to utilize a slabstat, I will have to reference the outside air.

SPA - Are you guys already seeing temps that mandate you turn your floor heat on??? I am usually good until Mid-December.

In the evenings its been down to mid 20's. should I hold off?

 

[Bubbles Galore]

I monitor it pretty closely, but until it is in the 20's during the evening rush wash hour, I normally leave it off.

 

[mjwalsh]

In the evenings its been down to mid 20's. should I hold off?

Turbo,

We are also in your specific area & so far we have only had to turn on our deicer once right after the snow after those recent 50-60 mph winds we had a little over 2 weeks ago. In fact it was the day Bill Pitzer our Forum Founder wisely held off leaving Bismarck until the weather finally got better! Welcome to the Forum!

MJ

 

[Rudy]

Search the forum for "two stat" floor heating.

I converted from a "slabstat" to a two stat system several years ago, and the payback is immediate.

There is an "air stat" that is set at about 34 degrees. At just above freezing, this stat starts the circulating pump.

A second, "return stat" senses the temperature of the returning fluid, and controls the "firing" of the boiler. Your settings may vary, but something in the range of 70-75 degrees keeps the slab ice free....and can be varied somewhat depending on the wind/severity of the cold weather.

This setup prevents the floor heat from coming on until it is very close to freezing....which is what we want.

On my old setup (single stat), the slab stat had to be set to something around 40 degrees in order to keep the whole slab deiced. If it was a constant 37 degrees outside, the floor heat would kick on even though it wasn't needed......which was a waste.

 

[Bubbles Galore]

Thanks for the explanation Rudy! How do you monitor the return line temp? Did you have to cut in some type of "T" with a well in it?

 

[SHINEY2]

Turbo,

We are also in your specific area & so far we have only had to turn on our deicer once right after the snow after those recent 50-60 mph winds we had a little over 2 weeks ago. In fact it was the day Bill Pitzer our Forum Founder wisely held off leaving Bismarck until the weather finally got better! Welcome to the Forum!

MJ

Thanks. Are you in Bismarck? Why was Mr. Pitzer here? [off track of this thread-sorry]

 

[Rudy]

To sense the return line, I used the previous "slab stat". It was a HoneyWell with a bulb-type end. I zip-tied it snugly to the return pipe and covered it with dense rubber foam insulation. Perhaps a "well" setup would be more accurate, but because it's copper against copper, the sensing seems to work fine, and has for years.

 

[Bubbles Galore]

A couple of more questions:

Can I use output 2 of my weepmizer to control my floor heat?

Maybe I have just not paid enough attention, but I am not sure that my circulation pump runs all the time. Did I just miss the boat and thats how floor heat systems operate when he initial setpoint is reached?

Thanks!

 

[Tpoppa]

I don't think you could use output 2 on the Weepmizer. Wouldn't that cycle on and off like the solenoid? It seems like the boiler could be running unnecessarily without a slab stat but, I've never tried that.

My floor heat circulating pump is always on, boiler is cycled on/off by a slab stat and a return line temp sensor. It's an old design, but it's simple and it works.

I bought a Tekmar 650 control that uses both a slab stat and air temp to trigger the boiler, but I never got around to installing it.

 

[Bubbles Galore]

Thanks for the input!

 

[mjwalsh]

Thanks. Are you in Bismarck? Why was Mr. Pitzer here? [off track of this thread-sorry]

Turbo,

In our truck bay we actually have 150 degree floor heat by our north door which surprisingly helps keep some ice off of that specific door through convection.

Yes, in Bismarck. To promote our brand new dog wash we have www.kingkoin.com. Mandan needed more options car wash wise. I hope they appreciate you taking the risk!

Bill was on I90 but went out of his way some & took I94 so he is a little more current with the upper Midwest where we are. He decided to drive the open road from the east coast Atlantic City NE Car Wash show to his home close to the west coast in Tri Cities, Washingtion. I know he stopped at Whale's in Fargo & I believe Bubble's in Michigan also.

MJ

 

[Rudy]

I think using Output #2 from your weepmizer would work. You'd want to use it (probably through a slave relay) to control the circulating pump. Having the circulating pump run continuously is a waste. Set the weepmizer to close a relay at 34 degrees starting your pump. Above 34, your pump is off, below 34, it runs.

Use the return line sensor to control the "firing" of your boiler. This way, when your slab is cold, you get "fire", when it's warm, you don't.

See my earlier post.

 

[car washing systems inc]

Yes you can use output 2 to controll your pump, you will need a relay and you can set it for a temp diff so it does not come on and off if the sensor is bouncing between you set temp.

 

[SHINEY2]

Turbo,

In our truck bay we actually have 150 degree floor heat by our north door which surprisingly helps keep some ice off of that specific door through convection.

MJ

You must have a different system then I do ??...my 2 thermostats [one for return line and one for slab temp] only go up to 100 ~? Just scared I will have freeze ups this winter. So far my bays even in the cold 10 degree weather have stayed around 35 to 40 degrees with them set at 38 degrees on the slab and 55 degrees on the return. If you think I should set it differently please say so, I trust your judgement. King coin is the best self serve wash in Bismarck - hope your dog wash is doing well for you! Thanks.

 

[mjwalsh]

You must have a different system then I do ??...my 2 thermostats [one for return line and one for slab temp] only go up to 100 ~? Just scared I will have freeze ups this winter. So far my bays even in the cold 10 degree weather have stayed around 35 to 40 degrees with them set at 38 degrees on the slab and 55 degrees on the return. If you think I should set it differently please say so, I trust your judgement. King coin is the best self serve wash in Bismarck - hope your dog wash is doing well for you! Thanks.

Turbo,

Each system has its unique characteristics & evolve in different ways. If a customer leaves a door open it could be a factor in even 10 degree temp depending on wind etc.

Indoors like that setting you stated & that was probably spec'd out at should be fairly close to what you need. The 150 degree of our system was done with embedded hose that can stand higher temperatures is indoors (just in front of the north truck bay door) along with our wall mounted 3 Trane Units with blowers that help get rid of the steam that forms from extreme cold air meeting the warmer air & from the car washing water vapor with the doors both shut.

Most of my system runs less than 100 degrees like yours except it is more outdoors just for deicing the front semi enclosed bays & it would possibly be too risky to run hotter water through some of that synthetic polyethylene pipe.

MJ

 

[JIMT]

We set our floor heat thermostat by using an infrared thermometer to check the temperature of the surface of the bay floors and adjust the thermostat to get the surface temperature between 35 and 40 degrees. Also, adjust the antifreeze flow in each circuit to get an even temperature across the bays.

JimT