car wash floor freezing up bad

[piperken]

This past 2 months our floor heat will not keep up with the ice build up. Im wondering if there is an air lock somewhere. our system had propolene glycol in it but ive been adding ethylene glycol at 50/50 so ive diluted it to 30%. Our boiler is 105000 btu per hour. im wondering if the boiler is undersized? any ideas out there. thanks

 

[Eric H]

I don't have my notes in front of me but I think snow melt\deicing calls for 80 btu per sqft. if your boiler is 105000 OUTPUT your floors are about 1312 sqft.
What temperature it the boiler supply temp? It shouldn't be over 130 degrees. It can run lower but should never run over 130 through PEX
What is the return temp? I find that 75-80 degree return works well for me.
Do you know the boiler pressure? I was trying to run one boiler at 9 psi but it wasn't enough pressure. My plumber told me to boost it up to 18 psi and some of my problems went away.

 

[PaulLovesJamie]

Also be aware that glycols lower your efficiency - ie the more concentrated your solution, the less efficiently they transfer heat to your floor. Meaning you need more btus.
Assuming that these freeze ups are a recent change, something like adding a bunch of glycol could cause that if you were near the edge.

 

[piperken]

there is no pressure at all, its all gravity. Im thinking about changing to a closed system with an expansion tank and running about 15 psi.

 

[2Biz]

If you have different zones, can you get temp readings with an infrared heat gun and report back outgoing and return temps from each zone? I'm heating about 1900sq ft of floor with a 199btu Condensing/Modulating Demand Heater. At 105° set point temp of the heater, it doesn't get out of low gear! (Lowest Modulation roughly 30K btu)...Keeps bays ice free down to and below zero no problem.

Sounds like you have other issues causing your problems. Start with what has been suggested. Need to see what outgoing and return temps are. This will be a good start in diagnosing your problem. BTW, I don't know if it is recommended to mix ethylene with Propylene....I run a 30% propylene mixture based on what Paul explains above.

 

[mjwalsh]

there is no pressure at all, its all gravity. Im thinking about changing to a closed system with an expansion tank and running about 15 psi.

Piperken,

I agree with all of the above responses ... except for that I would be somewhat cautious about increasing pressure too much. My gauge has always shown zero for the snow-ice melt system that we put in that was originally engineered by Raypak-Herm Deal (Huron Valley Sales ... Detroit) back in 1980. 50-50 glycol ... back then they recommended automotive glycol.

We use on a 12psi minimum overhead hot 50-50 glycol in Trane Unit heaters with their built in fans which clears fog out of the bays with over 120° F. That includes in the floor hose in revised concrete along the inside of our north RV bay door. The higher temps & heat rising actually helps keep the ice off of our RV accommodating Alaskan Polycarbonate OVD Door.

I looked up your average wintertime temperatures & it is somewhat similar to ours in Bismarck, ND USA There are many considerations that you have not shared with us ... like how much of your pad is out in the wind ... how many actual square feet? Do you have a flow switch on your system? I would think a properly sized & placed flow switch would reveal an air lock or lack of proper gpm flow.

Our system is around 2,000 sq ft. & is very much vulnerable to the wind. We have had way below average temps for about 6 weeks now & I will admit that our system does not always keep up where minus 50+ wind chill hits it. Just because there are slight ribbons of unmelted snow-ice does not mean that it is not safe enough for cars & person's walking across the "outside to the wind" areas.

Below is a link to a picture of our controls that allow us to accurately monitor the various parts of our boiler system. We found that 450K BTU step fired high efficiency hydro-multi-pulse boilers are enough since the greatest need for the deicer is during the night when the laundromat is closed & no prioritized domestic is calling. If you have access to copper portions of your system you can take manual readings pressing against the copper with the proper range thermometer with its probe as an alternative to 2Biz's infrared gun approach. The digital versions tend to allow you to switch from °C to °F instantly for reading purposes.

https://drive.google.com/file/d/1TA-sihZxYsHb5JSiE4v2PNS_kPLz1YQY/view?usp=sharing

 

[Rudy]

Although rare....the vanes on the circulating pump can degrade. It sounds like you have some impediment to flow....air, bad circulator...or a flow restriction of some kind.

Also...

Not so sure about mixing the pink and green glycol???

 

[Waxman]

FWIW: My floor heating boiler has a Spirovent like this :http://www.spirotherm.com/products/air-elimination plumbed in.

It seems to work great.

When I install a new furnace in my apartment building I plan to include a spirovent. I think it will reduce instances of the heat not making it to the 4th floor.

https://www.youtube.com/watch?v=YeG2mkNMzAw

 

[mjwalsh]

Waxman,

On our main boiler system ... we have a bunch of tiny air eliminators with an air valve on top with our system that mount on top of the highest possible pipes on a tee. They have a cap that we tighten down on them otherwise they leak. The good news is that once the air is out of the system it tends to stay out unless we add fresh water. The air valve looks just like what would be a valve stem on a car tire?

This other brand in this video might be a better alternative than the Spirovent ... not sure though???

 

[piperken]

the floors are out of the wind but my doors could be insulated to bring up the temps a bit. summertime its a drive through car wash and in summer we take down our wooden doors. Our total SQ is 1360. heated by a Weil and Mclean 105000 BTU output boiler. From what im seeing i think we use more BTU's.

Piperken,

I agree with all of the above responses ... except for that I would be somewhat cautious about increasing pressure too much. My gauge has always shown zero for the snow-ice melt system that we put in that was originally engineered by Raypak-Herm Deal (Huron Valley Sales ... Detroit) back in 1980. 50-50 glycol ... back then they recommended automotive glycol.

We use on a 12psi minimum overhead hot 50-50 glycol in Trane Unit heaters with their built in fans which clears fog out of the bays with over 120° F. That includes in the floor hose in revised concrete along the inside of our north RV bay door. The higher temps & heat rising actually helps keep the ice off of our RV accommodating Alaskan Polycarbonate OVD Door.

I looked up your average wintertime temperatures & it is somewhat similar to ours in Bismarck, ND USA There are many considerations that you have not shared with us ... like how much of your pad is out in the wind ... how many actual square feet? Do you have a flow switch on your system? I would think a properly sized & placed flow switch would reveal an air lock or lack of proper gpm flow.

Our system is around 2,000 sq ft. & is very much vulnerable to the wind. We have had way below average temps for about 6 weeks now & I will admit that our system does not always keep up where minus 50+ wind chill hits it. Just because there are slight ribbons of unmelted snow-ice does not mean that it is not safe enough for cars & person's walking across the "outside to the wind" areas.

Below is a link to a picture of our controls that allow us to accurately monitor the various parts of our boiler system. We found that 450K BTU step fired high efficiency hydro-multi-pulse boilers are enough since the greatest need for the deicer is during the night when the laundromat is closed & no prioritized domestic is calling. If you have access to copper portions of your system you can take manual readings pressing against the copper with the proper range thermometer with its probe as an alternative to 2Biz's infrared gun approach. The digital versions tend to allow you to switch from °C to °F instantly for reading purposes.

https://drive.google.com/file/d/1TA-sihZxYsHb5JSiE4v2PNS_kPLz1YQY/view?usp=sharing

 

[piperken]

the pump pulls the cooler water from the bays into the boiler just under the influence of gravity. It isnt under pressure at all like my system at home or some car washes. Im wondering if it will work better under a bit of pressure? right now there is a 6" pvc pipe resevoir above the pump that i use to top up with gylcol.