isolation solenoid enough to prevent liquid slugging?

[Poodle Head Mikey]

Box temp is for beer: about 35º

System now runs on R-22 - but with an R-502 TXV - because that's the closest orifice I could find for the distributor. Plus; I had the valve in the truck for decades and wanted to get rid of it. <g>

If I do not use pump-down - and just close the LLSV when the condensing unit shuts down - do you think that will be sufficient to prevent compressor logging in the evap during off cycles?

Right now it's not a problem of course as it's cold outside - but I'm thinking ahead to the summer.

[AiResearch]

We always called them a "drop" solenoid for non pump down , probly wired in parallel with the compressor contactor coil , Carrier was always a big proponent and used them for years and years in air conditioning to prevent migration during the off cycle and hopefully eliminate flooded start when used with a crankcase heater.

[Dad]

A low pressure control is cheaper than a new compressor Mikey. Why not install one to take the guessing out of the equation. It can be sold as a safety measure to prevent a huge loss to your customer later.

What kind of defrost control do you have on that system?

[Poodle Head Mikey]

Just off-cycle and clock-timed air defrost. The TD is fairly low - so not much to deal with.

About supper time I saw a friend of mine pulling into a bar and followed him in. I surprised him at the bar and ordered myself a Corona. The barmaid told me that the Corona was all warm because they keep it in the walk-in - which was broken.

So I said loud: Warm beer? What the hell kind of place is this? Where's your refrigeration guy? Why isn't he On This? We're talking about BEER for God's sake!

So the owner comes over and laments that the compressor is bad, it's very expensive ($6500. installed), and they can't get one for him until next week.

So my friend Dave pipes up (pointing to me): Next week? What are they talking about? I bet he can fix it tonight - from just what's in his truck!

So I laugh (you have to see my truck to really get the joke <g>) and say: yeah; probably could.

Dave says: I got a hundred here says he can do it.

(owner to me) Really? You know about this stuff?

Yeah; some.

And you can fix this walkin? Tonight? With just what you have with you? You're telling me that you have a compressor? With you?

Well; he says I can do it - I can't make him out to be a liar, can I?

The owner looks at Dave and says: Dave; I believe I'll take that hundred from you.

So I get the terms expanded to just what I have in the truck, PLUS the shop, and upped the bet to $200. with free cold beer for the duration - so long as I can fix it that night.

Of course I didn't have anything in the truck but I did think I had a 2HP R-22 condensing unit at home. But it turned out to be low temp. So what I actually installed that night was a used 2 ton York residential condensing unit and a fan center on an extended 1900 box. The R-12 coil's distributor had a R-502 orifice still taped to it and the closest TXV I had in the truck was for R-502 - 1.5 ton. I brought a little 13" accumulator too but I didn't install it.

120 volts through the NC contact on the time clock to the line voltage stat. Call from the stat powers the 120V solenoid coil and the primary to the fan center - sending 24V out to the compressor contactor.

First I added a transformer (luckily I didn't have a 240 volt contactor small enough <g>) and an LP control to the condensing unit but the damned compressor wouldn't start with the suction/discharge unbalanced. Even with a long time delay and nice hard start kit added.

So I yanked the transformer, ran a piece of two-wire out, and just broke the 24 volts from the fan center through the LP control.

Still; even with all the beer we consumed, I had it all up and running before midnight. <g>

SSH was a little high at about 28-30º but there is no suction line insulation either. The suction pressure runs about 50 lbs. and the head pressure runs about 150 lbs. but it was pushing midnight and I wanted to get it on-line so I didn't add a fan cycling control. By that time they were all trying to say that midnight was the deadline - not dawn.

And 150 head gives me 100 PD across the valve - so that's OK. But I have it on My List to go back and add one anyway.

I'm going back to add the HP control and change the driers and check the acid level. But it's a little far for me and I've been busy in the opposite direction.

But unless I replace the condensing unit again - I'm apparently left with no pump down. I was just puzzling over the lack of it maybe causing a problem later.

PHM
------

A low pressure control is cheaper than a new compressor Mikey. Why not install one to take the guessing out of the equation. It can be sold as a safety measure to prevent a huge loss to your customer later.

What kind of defrost control do you have on that system?

[rayr]

I sure would sleep a lot better with a receiver put on it and on pumpdoown. Suction line accumulater would be a plus also.

[Octopus]

Mike do you like being married to units?

[Poodle Head Mikey]

What gave me the idea was that many years ago in Puerto Rico I saw all kinds of walk-in boxes running A/C condensing units mated to Bohn and Trenton evap coils. I asked about it and my friend (in the refrigeration business there and in Florida) said: "they do it all the time here and they seem to run forever."

Still I wouldn't have normally done it. <g>

PHM
------

Mike do you like being married to units?

[chamberlain]

i like full pump down as much as posible you know your coil clear and no liquid

[Octopus]

Hey mike why not bring line above cond coil it will hold liquid in cond

[Poodle Head Mikey]

I'm not concerned for refrigerant liquid running into the evaporator as it's substantially higher than the condensing unit.

What I am curious about is: in a 35-40º coil - and say; a 90º outdoor ambient - will enough refrigerant vapor condense in the evap coil to reduce the evap pressure enough to continually induce a continued migration of refrigerant vapor to condense and collect in the evap?

And . . . will that collected liquid then arrive at the compressor as a slug at startup?

My spider-sense is saying: no.

But I wanted to knock the concepts around here with The Really Smart Guys. <g>

PHM
------

Hey mike why not bring line above cond coil it will hold liquid in cond

[Octopus]

I'm not concerned for refrigerant liquid running into the evaporator as it's substantially higher than the condensing unit.

What I am curious about is: in a 35-40º coil - and say; a 90º outdoor ambient - will enough refrigerant vapor condense in the evap coil to reduce the evap pressure enough to continually induce a continued migration of refrigerant vapor to condense and collect in the evap?

And . . . will that collected liquid then arrive at the compressor as a slug at startup?

My spider-sense is saying: no.

But I wanted to knock the concepts around here with The Really Smart Guys.


<g>

PHM
------

Mike seriously are you kidding me. You are one of the smarter guys.

[Poodle Head Mikey]

If I was actually smart I would have just laughed, ordered another beer, wished him good luck, and gone home to bed early. <g>

What am I proving?

Although; it was great fun showing off there putting some junk together and winning the bet.

One of my fondest memories is of winning a bet in a parking lot over being able to pick up a huge anvil and loading it into the back of a pickup truck. <g>

PHM
------

Mike seriously are you kidding me. You are one of the smarter guys.