Snowmelt System "stuck"/not responding?

Kinny

Hello,

I'm looking for some help here as I've tried to research online and haven't found any luck, including getting one of my gas guys is going to take a couple of days.

I have a NTI combi boiler (for hot water, radiant basement floor heating, and driveway heating), and recently, I noticed something is off. Over the Summer, I extended the driveway heating to the front steps (not a big increase in coverage) that's hooked up to zone 1, and it seemed to be working fine back in November/December, after they topped it up with glycol and completed the installation, however recently, with the colder weather and snowstorms, I noticed my driveway/front step melt function is not working properly.

This is a 4 yrs old home, therefore I don't know who the builder used to initially set it up, and the 7 flow valves that control each of the section isn't properly labeled. But in my case, the intake valves 2, 3, and 6 are warm and melting in their respective zones, however, 1, 4, 5, 7 are just cold. I tried to turn the dials to (-) for zone 2,3,6 to lower the flow (or shut off), and hope it'll increase the flow to zones 1,4,5, or 7, but it doesn't seem to be doing anything, even if I turn all zones to (-) while opening one zone to the max (+).

I can feel the intake is very hot, and the working zones/pipes are warm, however, the cold pipes/zones for some reason don't seem to want to warm up. Is there something wrong/blocked/air bubbles/frozen in the system that's preventing this? It should be all mechanical as I adjust the valves (-/+) to limit/increase the flow...but I really stumbled on this at this moment.

Appreciate your help and advice - thank you in advance!

Jack

STEVEusaPA

Was it installed, then bled with a purge cart?

Kinny

Thank you Steve for the quick response - I don't the system was bled, since they ended up topping up the glycol in the extended zone only, meanwhile leaving the rest of the driveway and basement radiant floor heating lines untouched. Once the new lines were filled with glycol, it was simply restarted.

Zman

Do you happen to know if the glycol % has been checked lately?
If you close all the loops but one, can you force the glycol through the one loop?
You are correct that feeling the pipes is your best indication of flow.
If you post some pictures we may be able to point out issues with the design or piping.

Kinny

I have not checked the glycol % lately but have tried to shutoff 1-6 and leave 7 on only but even after 1-2hrs, the #7 is still cold. Thought I could force it. 

Here are some pictures  I hope this helps  thx in advance!

Kinny

So when I turn down the other zones - adjust to (-), and turn up zone 7 as an example (+), the flow marker still stays at 0 for the “inoperable” ones. Meanwhile as I adjust the working ones, it responds to the change immediately. 

Here’s a top view pic of the adjust dials. 

Zman

It seems unlikely that only some loops would freeze. My guess is that it is airlocked. What is the system pressure?

Kinny

I’m not sure if I’m reading this correctly - from my boiler - although the snowmelt is off right now - the boiler says 13psi. My boiler works both hot water and floor heating. 

Zman

I don't like the way you have fresh water fill in a snowmelt system. If you get one leak, the fresh water will dilute your glycol.

You can check your glycol level with one of these. https://www.amazon.com/Brix-Refractometer-ATC-Dual-Scale/dp/B01LW2ZU6R

I like to see something like this on glycol systems to assure it doesn't get diluted
https://www.supplyhouse.com/Axiom-MF200-MF200-PRESSURE-PAL-Hydronic-Mini-System-Feeder-6-Gallon

HomerJSmith

Is it possible that either the supply and return manifold loop valves are turned off (closed)? Heavy glycol % can be hard to pump.

If you have a air vent on the manifolds, make sure they are open if the float type.

Too low a glycol concentration might turn to slush or freezing on a freezing driveway.

Kinny

thank you both zman and homerjsmith for the tips.

the supply/return loops are all open since they were all working probably 2 weeks ago and I haven't changed anything until the recent snowfall, where I noticed the uneven/not heated areas.

For the glycol % - I did ask the installer to check and make sure the glycol % is the same as what's in the system, and they said it should be fine... <-- Hopefully this is not the issue.

I don't have a float type, where it can auto-burp itself (definitely would be a plus), so based on where I'm at, I believe getting the right expert to come to take a look is better.

If you guys have any other suggestions/inspections/or things I can try, please let me know, thank you!

neilc

post a more distant picture of your manifolds,
is there any set up there to purge only at the manifolds?
or if you throotle down the working zones, can you get flow thru the dead ones?
any kids that like to fiddle with little black knobs?

Kinny

I believe I’m able to purge through the manifold - top right corner - that’s one of the release valve if I recall during their glycol fill. No kids have played with it and yes - I have tried turning everything off (to the negative) while leaving one zone on only - but it didn’t do anything even after an hour - with the Tekmar showing MELT). 

The below manifold picture was taken when the system was off - no snow/not activated by the driveway sensor.

EzzyT

Let’s discuss the elephant in the room the near boiler piping needs to be addressed since it’s all wrong plus then check if the system is air bound along with glycol percentage mixture.

Kinny

There’s a green box near the boiler and it’s a switching module that manages the 2 pumps. The driveway heating and backyard porch/front steps are in the priority zone/pump setting. So if the priority is not activated or doesn’t call for priority, then it’ll go to the 2nd pump to heat up the basement floors - if needed. 

Yeah I think I’ll definitely need to check the air in the system which may cause the air lock. 

Paul Pollets

This should be addressed by a pro who is familiar with snow melt systems and has a flush cart. After flush and purge and adding correct antifreeze. Near boiler piping should also be repiped.

Kinny

Thank you all! Yes - I’m looking for a contractor who can help - at this moment they are scheduling for late next week. 

It’s great knowledge you guys are sharing so I have some background to help make an informed decision in the future. 

In regards to the boiler area repiping - what do you mean? What’s the issue?

thank you!

Kinny

Also question - what’s the right glycol/water mixture? Are there multiple types? I guess it’s based on usage application. 

Kinny

hmmm is that a water line that’s connected to the glycol pipes? Does that mean it’s diluting the glycol over time? Why would someone do this?

Kinny

The white pipe with a green shutoff valve. 

Zman

Zman said:

I don't like the way you have fresh water fill in a snowmelt system. If you get one leak, the fresh water will dilute your glycol.

You can check your glycol level with one of these. https://www.amazon.com/Brix-Refractometer-ATC-Dual-Scale/dp/B01LW2ZU6R

I like to see something like this on glycol systems to assure it doesn't get diluted
https://www.supplyhouse.com/Axiom-MF200-MF200-PRESSURE-PAL-Hydronic-Mini-System-Feeder-6-Gallon

Kinny said:

hmmm is that a water line that’s connected to the glycol pipes? Does that mean it’s diluting the glycol over time? Why would someone do this?

That is what I was getting at...

Kinny

Thx zman!  I don’t understand what’s the purpose of that line attached to the glycol - closed loop system… what’s it supposed to do?

Kinny

I've got a question, I opened the black rubber cover on my driveway today, but there are no wires inside or a "sensor" that I can see. It's simply a hollow cavity. Whoever who did this job, did they purposely missed something or is it more of a potential future upgrade?

ratio

Looks like that's the body for a snow sensor. If you're going to start it manually whenever it needs to run, I don't think it's absolutely necessary, but it (or another sensor) is needed for it to start automatically. I wouldn't want to be running over that plastic cap with my car, either.

Kinny

right, so this means right now, there's no actual sensor under this sensor holder/black rubber cap... huh. I feel like whoever did this snowmelt system did not know what they were doing, or cheaped out.