Need help with floor heat

[Nelson B]

What are the disadvantages of installing a thermostat in the concrete in a bay for the floor heat? we have a stat for the outside temp but the front side of the wash faces the south and naturally melts by mid morning by the sun. is it possible to only run the floor heat by the thermostat in the floor and how is it done. need advise please. thanks

 

[JMMUSTANG]

All my washes floor heat thermostat are in the floor.
Just make sure that they are not to deep, closer to the surface.

 

[dogwasher]

The thermostat should be installed in the concrete, sounds like it was installed incorrectly. Normally when they pour the concrete the HVAC installer would have placed a piece of conduit/or a tube from the mechanical room (few inches below the concrete) 3 or 4 ft out into the outside bay. You could try to drill a hole to slide in the thermostat in a good spot to sense the cold concrete.

 

[Ric]

My floor heat was set up that way initially. I found it be more accurate to sense the return line temp. going into the boiler. I have a separate thermostat on the pump which reads the air temp. It will turn the pump on at 37 degrees (air temp). The burner then runs off the temp of the return fluid line which will be set to a lower temp.

 

[Bubbles Galore]

My floor heat was set up that way initially. I found it be more accurate to sense the return line temp. going into the boiler. I have a separate thermostat on the pump which reads the air temp. It will turn the pump on at 37 degrees (air temp). The burner then runs off the temp of the return fluid line which will be set to a lower temp.

I do the same thing and have found that to be far more efficient.

 

[Earl Weiss]

My floor heat was set up that way initially. I found it be more accurate to sense the return line temp. going into the boiler. I have a separate thermostat on the pump which reads the air temp. It will turn the pump on at 37 degrees (air temp). The burner then runs off the temp of the return fluid line which will be set to a lower temp.

How much lower. Does not seem like it should be below 32 or maybe even 34 to keep it above freezing.

 

[bigleo48]

The added benefit in reading the return glycol temp is that you can control how much heat is applied to the slab, thus slowly heating up the pad to prevent cracking it.

 

[Tpoppa]

I have 2 thermostats. A slab stat and a return line stat. It works quite well.

 

[mjwalsh]

Relevant Controls & Resources Comment Relevant to Thread

What are the disadvantages of installing a thermostat in the concrete in a bay for the floor heat? we have a stat for the outside temp but the front side of the wash faces the south and naturally melts by mid morning by the sun. is it possible to only run the floor heat by the thermostat in the floor and how is it done. need advise please. thanks

Nelson B & others,

I hope this helps --- hopefully operators see the usefulness based on 31 years of actual experience --- in an area that has the need for a minus 30 degrees below zero Fahrenheit deicer design.

My controls are bit more sophisticated than what has been expressed so far. I do not regret redesigning the system --- so both the slabstat & the return temperature are a factor. If it was controlled just by the outdoor temp &/or the return temp --- I see a potential problem of ice remaining or forming even though the outside temperature & the return gycol is satisfied.

I might be able to trust --- just the return glycol temp based on the fact that the slab would tend to cool the "return temp" in direct correlation to the slab temperature. I see it is less risky & just as efficient to use both indicators within the controls though. The outside air temperature is less relevant in my opinion because if there was a quick very temporary spike upwards of the outdoor temperature --- there could still be potentially ice forming in shaded areas.

Sensitive enough controls (response time included) is also a factor. The original design & control that came with the system had too much of a differential between start & stop & had a really crappy response to the change of conditions!

Our modular Independent Energy Goldline controls also physically display the actual temperatures --- so we can notice "if we so choose" as we walk by --- plus they have alarms that audibly alert us if a specified temperature is reached --- posing whatever risk.

Earl --- if the federal government would do what it's role actually is supposed to do --- the odds of a greater percentage of us(coin op self serve) having the resources to stay on top of our operations similar to what Nelson & this specific thread is after --- would be better. Specifically optimizing our controls for both safety & energy conservation wise! That is my observation of the current state of affairs coming from some in the administration & congress towards our livelihoods & jobs in general. Choosing lesser studies & clearly less credible surveys "is breaking the camel's back for me"! Less $5 bills in circulation because of too many $1bills hanging around for much too long --- is definitely not helping the majority of us operators to stay on course with the relevant controls that we should be using for our self service non automatic infrastructures as Nelson Bs thread relates to!

Continued on next post

mike walsh king koin of bismarck

 

[mjwalsh]

Continued from previous completely relevant post!

"Continued from previous post

To get off the subject a bit --- our PLC driven dog wash has the ability to show its Ethernet connected set up & monitoring screen remotely so we can see the temps on a smart phone via whatever sort of remote desktop used. So we also can see a potential for remote alarms or a quick text message or whatever along the line of those kinds of useful alerts.

The above capability should exist without nickel & diming monthly charges in addition to our ethernet & cell phone monthly charges --- in my opinion. Those "opportunists" trying to milk anything & everything from us should stay focused on better "VALUE DRIVEN" things --- in my opinion & based on actual experionce as always --- of course!

mike walsh king koin of bismarck

 

[Earl Weiss]

Nelson B & others,



Earl --- if the federal government would do what it's role actually is supposed to do --- the odds of a greater percentage of us(coin op self serve) having the resources to stay on top of our operations similar to what Nelson & this specific thread is after --- would be better. Specifically optimizing our controls for both safety & energy conservation wise! That is my observation of the current state of affairs coming from some in the administration & congress towards our livelihoods & jobs in general. mike walsh king koin of bismarck

HOLY FRIJOLE had to read a few lines to see how the Fed. was involved with our floor heat setup.

 

[MEP001]

Less $5 bills in circulation because of too many $1bills hanging around for much too long

I think he's trying to steer the thread toward his $1 coin agenda.

 

[Tpoppa]

I think he's trying to steer the thread toward his $1 coin agenda.

Will $ coins prevent ice build up in my bays

 

[Earl Weiss]

Will $ coins prevent ice build up in my bays

Try and make a fire with Dollar coins

 

[Washmee]

Try and make a fire with Dollar coins

 

[mjwalsh]

It costs to tap in into needed engineering resources-GET IT!

The thermostat should be installed in the concrete, sounds like it was installed incorrectly. Normally when they pour the concrete the HVAC installer would have placed a piece of conduit/or a tube from the mechanical room (few inches below the concrete) 3 or 4 ft out into the outside bay. You could try to drill a hole to slide in the thermostat in a good spot to sense the cold concrete.

Dogwasher, Nelson & others,

If that is the case that the installer did not make a provision to be able to replace the temperature slabstat sensor --- then I personally would use my already owned 4 1/2 inch grinder with an already owned or easily purchased diamond cutting wheel. I would make a V in the cement with it & then encapsulate the tube with a good patch concrete material. Hopefully, you can find a spot where you can go a minimum length. If it is possible Dogwasher'S statement of drilling into from the outside of the slab would of course be the first choice. When we redesigned our controls we used a thermistor to insert into our pre-existing concrete embedded tube.

Tpoppa & others --- YES, with more $5 bills showing up in your bill acceptors --- & with proven more reliable acceptance of properly available $1 coins --- most coin op self service wand type of operators will be in a better position to have more resources to deal with the heavier infrastructure items such as putting in & maintaining a de-icer system --- especially in the tougher northern climates.

This also is related to Nelson's thread from a resource standpoint --- at the beginning of this heating season --- we hired a large contractor to assist us with some boiler work. On their bill it specifically had sales tax on their entire bill even though there was no parts used --- only labor. Knowing the specifics of the applicable law --- you better believe --- I was in their face --- & made them correct their error.

mike walsh king koin of bismarck

 

[Mr. Clean]

I've been thinking about installing an ambient air thermostat wired in series with the slab stat to increse the sensitivity. The thought is that the slab doesn't get heat if air temp is above freezing during the day. Most of the time the slab stat has to be set close to 38-40 to adequately prevent icing, but when air is above freezing it's not necessary to have it on, so this configuration would cover both scenarios without having to adjust manually.

Does this make sense? Has anyone used this configuration?

Thanks.

MC

 

[dogwasher]

My floor heat was set up that way initially. I found it be more accurate to sense the return line temp. going into the boiler. I have a separate thermostat on the pump which reads the air temp. It will turn the pump on at 37 degrees (air temp). The burner then runs off the temp of the return fluid line which will be set to a lower temp.

Sounds OK but I don't like the fact that the pump is running continuously and depending on the type of boiler you have you also run the risk of the exchanger condensating from the cold water flowing threw the inside of the warm mechanical room "possibly shortening the life of the heat exchanger.
When its below freezing outside my stat can be satisfied and the complete system off for a good amount of time before it calls for more heating of the slab.

 

[mjwalsh]

I've been thinking about installing an ambient air thermostat wired in series with the slab stat to increse the sensitivity. The thought is that the slab doesn't get heat if air temp is above freezing during the day. Most of the time the slab stat has to be set close to 38-40 to adequately prevent icing, but when air is above freezing it's not necessary to have it on, so this configuration would cover both scenarios without having to adjust manually.

Does this make sense? Has anyone used this configuration?

Thanks.

MC

MC & others,

In our area with the 2 wired in series --- unless your system really keeps up & the slab never gets behind temperature wise it could work. My specific system does sometimes gets behind --- to me it is certain there would be situations where a very temporary Chinook wind came in shutting down the sytem prematurely based on the outdoor temp. Again, shaded areas will play a role.

If the 2 were wired in parallel then --- I see the slabstat possibly getting a jump on turning on --- which may be helpful --- especially if the system was sized a bit small. I agree on the 38-40 degree temps necessary during the coldest --- really low wind chill times. If my system does not quite keep up during a really bad blizzard it is not all bad because the car wash should be closed then --- & the crust of snow helps to make sure the heat loss is not quite as drastic. It is a non issue in the bays that are totally enclosed with Airlift polycarbonate doors. There --- we have inside & in the northern part of our truck bay a loop of very hot over 140 degree temp glycol that with convection actually helps to keep the ice off the one large 11'-13' NORTH door. That same over 140 degree glycol flows through 3 Trane hot water Unit Heater mounted about 10 feet in the air.

There are variables on how the car wash is in the prevailing winds etc. I do agree with Dogwasher on the potential for a condensation issue. One mechanical engineer took the time once to explain to me what can also happen to some boilers with a "thermal shock" situation.

One thing that I mentioned before on the forum --- but has been awhile --- running glycol directly through a boiler will drastically decrease its efficiency. One of our better less wasteful decisions was to use a couple of French made Spirec http://www.spirec.com/ heat exchangers so the modular sequence controlled boilers could have regular boiler water as much as possible.

MikeW

 

[Ric]

Sounds OK but I don't like the fact that the pump is running continuously and depending on the type of boiler you have you also run the risk of the exchanger condensating from the cold water flowing threw the inside of the warm mechanical room "possibly shortening the life of the heat exchanger.
When its below freezing outside my stat can be satisfied and the complete system off for a good amount of time before it calls for more heating of the slab.

I see your point. In the 28 years I've operated my floor heat boilers in this fashion I have not experienced condensation within the heat exchangers. I have a 4" fresh air vent going directly to the boiler. My wash faces north/south. So half the wash slab gets sun (when available). I feel that by running the circulator pump ahead of the burner set point that I am moving some of the "solar" heat around.