Grocery store mech. equip. , first for me

[coolerinfrederick]

fellas dont bash to hard, my carrer has been in resid. and light commerical for 7 yrs., and i recently hooked up with a all commerical co. and lovin it, pay is very good and work is laid back, anyway got sent out too a closed down groc. store to survey their Mech. equip., as i walked in the store i noticed a set of blueprints for store on a table, sweeet i said, as i was going over the mech. plans i noticed several things that stood out that i'm not familar with, the ahu specs are: 1) heat reclaim coil which is part of the refrigeration system for the store, as i understand it the heat energy that is gained in a refrigeration system can be used for basicly free heat and all the great advantages, this coil had 5 circuits feeding it, each circuit has 1 line insulated and the other refrig. line not, the non insulated line also had a head press. control from sprolain and it looked all copper with an adjustable screw on top, i think i've seen in a book some where, what is the purpose of it? other than to maintain a desired press.



the ahu also has a dx coil as well, with two 10 ton condensers piped to it,
heres where i get stumped/ in between the heat coil and dx coil theres a mixing box which is ducted to the supply to a outdoor air unit, which has no blower just a evap coil, there are 3 more 7.5 ton condensers piped into this unit, and the controls just doesnt seem too eff. and are not unit safe friendly


anybody care to share their knowledge

[icemeister]

It appears what you have is similar to what we call a dual path system.

Here's a PDF from Seasons-4 that explains it fairly well:

http://www.seasons4.net/dualpath.pdf

[coolerinfrederick]

simialar but not quite , the equipment is 28yrs. old, ((( GE)))

[jogas]

Been a while since I did any supermarket work, but....
The reclaim is for heat AND dehumidification (the reefer cases spec an ambient temp/humidity for best operation). The reclaim will also need to be flushed every so often as oil/refrigerant can/will migrate there. The Sporlan is probably a hold-back valve to keep the head (or suction) up.
No idea on the summer OA/DX setup other than makeup air to offset exhaust, maybe for the bakery?
jogas

[icemeister]

http://coastepa.apogee.net/ces/library/btssd.asp

[Phase Loss]

the ahu specs are: 1) heat reclaim coil which is part of the refrigeration system for the store, as i understand it the heat energy that is gained in a refrigeration system can be used for basicly free heat and all the great advantages, this coil had 5 circuits feeding it, each circuit has 1 line insulated and the other refrig. line not, the non insulated line also had a head press. control from sprolain and it looked all copper with an adjustable screw on top, i think i've seen in a book some where, what is the purpose of it? other than to maintain a desired press.

I am going to assume that the insulated lines are your "inlets" to the reclaim coil, they are trying to minimize the minimal heat loss on the pipe run to the reclaim coils...now you have the "un-insulated" lines, im going to assume that they are the "outlets" from the reclaim coil and come out through a p-trap. than into that "sporlan valve with an adjustable screw on top" that valve is indeed a "hold back valve" the purpose of this valve is to maintain a minimum pressure in your reclaim coil. where i work, we require this hold back valve to be set at 90* converted. because supermarkets strive to run lower head pressures to reduce kWH often times the running head pressure is around 75* converted. and you just simply cannot heat a store with such a low pressure. so that being said...if you are running a heat reclaim coil and that hold back valve is in play...that "free" heat is no longer "free" because you are creating a false head pressure by holding back pressure in the reclaim coils causing a higher head pressure causing a higher compression ration causing higher kWH...Many markets where i work are removing the Hold back valves and installing gas furnaces.

[coolerinfrederick]

very good information, thank you, and you're right stores just arent doing this anymore, like i said, first for me, hey found lots of work to keep me busy during this slow time, we will be replacing a rtu, compressor for one of the condensers, coil cleaning and the list goes on, i'll be there all next week