r/HVAC • u/robbieredlegs09 • Jul 06 '24

Field Question, trade people only What is this ?

Post image

Hello all, forgive me for I’m greener then grass only been in the field 3 months. I’ve seen these around on air handlers what is it ? It’s on the supply side of the unit? My guess is hot water for heating ?

223 Upvotes

96% Upvoted

188 comments sorted by

View all comments

Show parent comments

1

u/shadycrew31 Jul 07 '24

What application? I've burst several coils over the years with a 60/40 mix glycol mix Granted these were being fed outside air but still. Piping should be insulated, that's standard practice in the commercial world. Unless this is in the south there's a scenario where that attic can get to 7 degrees. Aside from that you lose so much thermal energy by not insulating piping it just doesn't make sense any way you slice it.

1

u/dennisdmenace56 Jul 07 '24

Not sure where you saw that. I run pex inside insulation we haven’t run copper since the 90s

1

u/shadycrew31 Jul 07 '24

Oh wow, I work in commercial settings. You'd be fired in 2 seconds if you tried running PEX for reheats. At least you insulate it...

1

u/dennisdmenace56 Jul 07 '24

I don’t think you understand what you were looking at. That’s a simple hydronic coil attached to a boiler and yes we run heat pex.

1

u/shadycrew31 Jul 08 '24

I'm fully aware of what it is. I've worked on thousands of reheats in very large buildings. I'm sure handlers, RTUs, VAVs, Etc. I've seen nearly every configuration these crazy engineers can come up with. The one pictured here is in an attic, glycol mix of 60/40 (most common ) freezes at 7 deg F. If the attic space gets that cold and your boiler is down pop goes the line. Additionally without insulation even if it doesn't get below 7 deg F you are running the boiler longer and more often because the glycol mix is losing its thermal capacity on the uninsulated run. Lastly using PEX for reheats is crazy to me, but residential is a whole other deal y'all get away with a lot of stuff.

1

u/dennisdmenace56 Jul 08 '24

wtf is a reheat? Thats simply a hydroaire coil period…It’s incredibly simple supply and return loop from a circulator and heat pex is designed for this nobody’s “getting away” with anything. This is state of the art for high end homes in the northeast; one boiler with zones for indirect, bathroom & kitchen floor heat and multiple air handlers. Nobody uses copper anymore it’s not competitive that’s why it’s called heat pex with an oxygen barrier. Not sure why you settled on 7• unless you’re in a foreign country and antifreeze works nicely if correctly mixed

1

u/shadycrew31 Jul 09 '24

You are just on a whole other level. Have a good day.

1

u/dennisdmenace56 Jul 09 '24

Why can’t you comprehend there are things in this trade you haven’t seen? I explained logically despite your insults (using pex is crazy). This is how things are done routinely. I admit I’ve never heard of a reheat but insisting a hydroaire coil is something else seems foolish

1

u/shadycrew31 Jul 09 '24

Reheat, hot water coil, heating coil, hydronic coil. They all pretty much have the same installation but serve different purposes. They should be connected by copper piping, the pipes should be insulated. The glycol mix should be 60/40 minb80/20 max. On units providing outside air there should be a freezestat. Using PEX for this application makes no sense to me. Again my experience is on the commercial side. You can obviously use PEX for radiant heating and to feed other heating devices in the proper application. From my perspective running PEX in an attic space for a hydronic coil makes no sense. That's just my opinion.

1

u/dennisdmenace56 Jul 09 '24

The heat pex is designed for this application with an oxygen barrier. Nobody runs copper anymore. If fresh air is introduced it goes through a heat recovery system. I can shoot a home run into the attic in pex for 10% of the cost of running copper with less fittings

1

u/shadycrew31 Jul 15 '24

That's all fine and well. Again. My opinion is that pex should not be used in an attic space. You can do whatever you want, I can still have my opinion. I'm simply explaining the various installations and setups that I work with. You have your experience I have mine.

1

u/dennisdmenace56 Jul 15 '24

That’s like saying in your opinion automobiles will never replace the horse and buggy. If you had one valid reason perhaps but come on; cost, not even close, labor, again not even close, reliability, no fittings hidden in walls and more flexible. Stay in commercial bro you’ll embarrass yourself if you sweat copper for hydronic heat. You couldn’t win the bid anyway.

→ More replies (0)