Freeze pump on 100% OAU
Installed a freeze pump for a 100% OAU. Dual temp coil. It has frozen 2 years in a row. More pics to come.
Motor starter has HOA. Hand runs pump 24/7. Auto runs thru a Tstat set at 40* to run the pump even unoccupied.
Sent from my iPhone using Tapatalk
New piping from the tee on the supply to the bottom of the actuator flange on return
Sent from my iPhone using Tapatalk
What happens if the pump knocks off? There should be a freeze stat to shut off the fan and open the valve for full flow if the temp get below 38 deg anywhere in the air stream. Just finished a similar job and I had the control guys bring the pumps on at 45 deg just to make sure no freeze stat trips.
Face and bypass coils are the best for 100% oa units. Just open the valve 100% and modulate how much air goes through the coil. Especially with a steam coil.
Pipe work looks good.
The unit has a freeze stat that;
Closes o/a damper. Opens control valve 100%. Shuts the fan off.
I tested operation and verified it worked. First time seeing the unit, the county takes care of it.
I installed new coil and a freeze pump per their request.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
That is some clean work Gravity!
Nice job on adding OC protection to the control circuit since it leaves the panel
Sent from my iPhone using Tapatalk
Post Likes - 1 Likes, 0 Dislikes
use oily rag on pipe to prevent solder drips?
Keep it simple to keep it cool!
Originally Posted by
stanbyyourword
use oily rag on pipe to prevent solder drips?
Just dont drip
Sent from my iPhone using Tapatalk
Originally Posted by
stanbyyourword
Good job then
Actually, if i have a drip about to occur, i wipe/flick it with my finger on my pants. Lol
Sent from my iPhone using Tapatalk
Pro Press all the way now!
Nice Job as well!
Originally Posted by
pecmsg
Pro Press all the way now!
Nice Job as well!
Dislike
Sent from my iPhone using Tapatalk
Originally Posted by
gravity
Dislike
Sent from my iPhone using Tapatalk
curious what type of solder you use?
How did you select the pump?
Last edited by GoCougs; 08-24-2019 at 11:46 AM .
Sterling 95/5
Nokorode paste flux
I was given specs of the coil. Freeze pump i was told to design at 1/3 of gpm of coil
51gpm coil
17gpm at 15ft/hd
Went on wilo website, plugged in numbers and found the smallest pump i could use.
Sent from my iPhone using Tapatalk
A job the fitters are doing for us.
The labor savings more then make up for the cost of the fittings!
Attached Images
Installation looks good but a power failure coils done. Plate hx pump and expansion tank and glycol the only 100% way for protection.
Originally Posted by
servicefitter
Installation looks good but a power failure coils done. Plate hx pump and expansion tank and glycol the only 100% way for protection.
Thats a pretty good idea.
If they just switched to glycol. Everything would be good
Sent from my iPhone using Tapatalk
Originally Posted by
servicefitter
Installation looks good but a power failure coils done. Plate hx pump and expansion tank and glycol the only 100% way for protection.
What protects the waterside of your system when the power failure occurs? Our coil is good, but the boiler and our new hxger are leaking water....
Originally Posted by
gravity
Thats a pretty good idea.
If they just switched to glycol. Everything would be good
Sent from my iPhone using Tapatalk
Problem with whole system treated with glycol is more pump is needed, less heat transfer ,cost of glycol and the maintaince.
Originally Posted by
gravity
The unit has a freeze stat that;
Closes o/a damper. Opens control valve 100%. Shuts the fan off.
I tested operation and verified it worked. First time seeing the unit, the county takes care of it.
I installed new coil and a freeze pump per their request.
And it still froze? This is the cooling coil right? Do they not bring on the CHW pumps in freezing conditions?
One theory; if the damper isn't darn near perfect the other units running in the building may still pull OA through the unit causing things to freeze.