dialing in a snowmelt sys with issues...

hot_rod

I know Dow does, maybe Nobel or Hercules. Dow gives you directions for sending samples in their Engineering Guide, maybe at their website. Generally you have Dow reps in major cities.
In Salt Lake there are a few large chemical companies, Huish rings a bell. Look up chemical suppliers. Maybe a lab at the Uof U?

Hercules the folks that make rocket fuels are out west of Salt Lake, I know they have chemical engineers :)

hr

Timco

I have a large snowmelt system that needs help, er, I do. 6 zones, very well built, but installer put the tek sensor right in the sunniest part of the drive. Control is tek 336(? I forgot the number) and each zone has a landis / gyr 3-wy valve control. Is there a way to set the landis controls to help overcome the issue of sensor placement? I get there and the main drive is dry, but shaded areas are ice & snow. I have nevr seen these landis controls, they have a scale from 40 to 120. Did not find any lit on them. Maybe a longer run time and set the landis controllers to allow these trouble areas more time?

Tim

Mark Eatherton

12 hour twist timer...

Tim, whenever I do a SM system, I always include a 12 hours twist timer for numerous reasons.

First reason is because, like your situation, regardless of where the sensor is placed, it can't see all conditions and will be wrong 50% of the time.

Second reason is that snowmelt system work much better PROactively then they do REactively.

The LG control sounds like it is just a 3 way mixing valve, and should be set for 120 degrees F.

Based on the quality of work, I'm guessing that Ken Barney and Clay Thornton had something to do with the installation. (Thornton P&H). THey keep some pretty good records. You could probably call them and ask them questions on the system.

I also recommend a 12 hour disable timer. In the spring, there are some fast moving wet snow storms that may wake the melting giant, when it is really not necessary. The 12 hour "ignore" timer does just that. It ignores the snow and saves energy.

ME

hot_rod

some snowmelt sensors

Caleffi comes to mind, allow multiple sensor locations for zoned snowmelt control.

hr

Timco

Thanks for the replies. The sensor is a temp / moisture / snow type tekmar and the control has one touch on & off. I have the one touch on feature set to 8 hours and idle is 31*. WWSD of course. I thought the Landis control would pinch off zones with warmer return temps, and let the heat go to colder zones, no? Would there be a benefit to leaving all zones 3-wys open at all times? What return temps are avg for snowmelt?

Tim

Timco

Hey ME,

Thorton may have done it but the job was done in '89. New boilers and sensor were done last summer, and he is a joke and was let go. He did this:

Side note: This 'leak' was huge, and lost a lot of glycol, but did not kill the grass. Might this tell me what type it is?

Tim

Mark Eatherton

Tim

Did he core drill the slab to set the sensor? If he did, that is probably where the hole is...

You have mod con boilers there, and a tekmar 667, which is a top of the line controller. Am not familiar with the LG controls, but I suspect that they were put in to protect the boiler, or the slab, or both. That is not necessary any longer.

If your input is less than 150 btu's per square foot per hour, the chances of you thermally shocking the slab are slim to none, and the boilers LOVE to see cold return water. If all zones are properly balanced and installed, they will all come up to temp evenly, so no benefit of having them shut down as they hit their target.

Idiling any snowmelt slab is expensive. During a clear night sky condition, the slab is projectile PUKING btu's into outer space at an accelerated rate.

I'd get rid of the idle. You can program the control (dipswitch setting) so that it is in MELT mode whenever you input voltage to the aux. demand contacts. Connect that to the twist timer and can the idle feature, unless these people can afford to burn money to keep their driveway snow free, in which case, they don't need a snowmelt system, just someone to keep the piles of dollar bills lit :-)

Finding and fixing the leak is going to be a challenge... Maybe you should convince them to hire me and you to get the job done :-) Have bags (and GPS) and will travel.

ME
Mechanical Systems Consultant

Mark Eatherton

Other bad news...

In this case, it probably does not matter, but the straight pipe distance before and after the secondary input form the modcons is not right. Supposed to be a lot more straight pipe before and after the twin tweener tees. He obviously had some "issues" with the soft soldered joints there too eh...

It also appears that there may have been a potable water make up on the system at one time. I hope not, or your leak issues may have just begun. If the system went through inadvertent dilution, the tubing may have been frozen, and broken. Not a pretty sight, and no way of effecting a good repair short of jack hammer surgery ;-(

You've got a pump installed up side down on one of the boilers too...( J box down).

ME

Timco

Well, he already 'fixed' the leak where he chipped into the slab loop. The re-pour looks terrible and I may be asked to fix that. System has a hose to hook to water and a pump for glycol fill, but holds pressure. small leak now at the close tees I will fix in spring. I can see where no need for the landis / gyr controls. It heats well, and house manager wants the idle so it will melt fast in case owner shows up for first time in just over a year now. Whole house is a tax deduction I think. Every 90% furn leaked at condensate collection box, 6 total. I think leaving all 3-wy valves open will make it heat better...

Tim

MIke_Jonas

Help me here..

I don't mean to hijack a thread or go off topic, but if I don't ask I won't know.

I cringe when I see the copper bushed down for that air sep, then bushed back up.

The job looks like it was beaucoup dollars, but that air sep screams somebody cheaped out.

I don't mean to fixate on rearranging the deck chairs on a sinking ship, but when I see stuff that like, my mind goes into overdrive, thinking what other corners were cut that I can't see.

Do you guys look at it the same way or do I have my undies needlessly in a knot over nothing?

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Mark Eatherton

The only saving grace....

is that its a micro bubble resorber, which is not as subject to velocity issues as a conventional scoop would be.

But you're right, he cheaped out.

Should have used a tangential separator for a lone that large.

ME

hot_rod

I'd check the air eliminator

also. Looks like at least 2 sizes smaller than the pipe size. a 1-1/4 has a Cv of 38. A 2" Cv 53.

With HDS software you could determine some of those flow issues.

Excessive velocity through that device may wear the "whiskers" right out of 'er. I'd size it to the flow rate required when repiping.

hr

Kirk_4

Putting in an automatic glycol feed pump is a good way to monitor that small leak. It will let you know exactly how much fluid it's losing.

Timco

Ahhhh, the beauty if the inherited job. The guy who installed the knights is a lameo, period. He rubbed red silicone all over condensate collectors in the furnaces where they were leaking rather than the real fix of new collectors & gaskets like I did. Not a drop now. The system does run very well, hard to justify a new micro bubbler when it runs well. Just goes to show why he was let go...Did someone know how to ID the glycol? If it does not kill grass, might be the food safe type? I would love to know which scale to use on the refractometer...

Tim

hot_rod

IDing glycols

the only way to determine if you have PG or EG is to send it to a lab. No meter you can buy will show you what you have.

EG and PG can be blended without a problem, however the toxicity becomes an unknown.

EG (DowTherm for one)is a better transfer fluid, less expensive and commonly used on larger capacity systems. Any empty containers around the jobsite?

It, EG, does have a higher oral toxicity rating, but does actually break down in the enviroment faster than PG, one less carbon.

Regardless you would be wise to contain any spills EG can and will harm of kill animals that may drink it. I'm fairly certain the original installer would have used PG.

If and when you repipe to fix leaks, upsize the air eliminator

hr

Timco

I am currently asking around, but who tests glycol types? Any ideas who would test this? I would like to do this right...

Side note: I found 2 very large manifold stations out in the landscaping in ground vaults. I knew I had more pumps than manifolds!

Tim

Mad Dog_2

The one Mark designed for us........................

Incorporated that twist timer and I'm glad that we did.......slab sensors and roof-mounted snow sensors were hit and miss. Mad Dog

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Timco

I thought of the U first, but Joan is in Anthro dept and does not know anyone from chemistry. We are going to take a sample down to below freezing and see where it freezes. based on that, and what the refractometer says, I will know which it is. I like experiments...

Tim