1985 Trane RTU w/ HW W973 & t7067

[richvacr]

I have this trane SFHB250 rtu with Honeywell W973 Energy management & a T7067 thermostat transmiter. The problem, besides a dead compressor, is the working compressor would not come on. Being late on a Friday I bypassed the W973 control and put in a t oggle switch at the thermostat so at least they have cooling.

So now I have to go back and get it working - replace comp. and figure out what is wrong with the controls. There is a chance that the discharge air sensor is bad. I think I had a reisitance of.80kohms which after I found the literature is off the chart.

what i would like to do, already got the no way of replacing the unit, is update the controls - like a 2 stage thermostat. I would like to keep the economizer. What I read so far the w973 may not work with a digital thermostat.

anyone here have advice or better what wiring changes are needed

[lipsoffurry]

Wow, it amazes me how much old junk is still running. You really may want to think about selling a new I-Pak. The word is the footprint is going to change and the new product will need a curb adapter. Jay may know when....Your customer has gotten his money from that unit.....24 years...Bet you don't have much steel left in the rail...Pick it carefully.

[maxster]

forget the W973 just control the cool 1 cool 2..3 and 4 if you have them with a new staging control that system is 20VDC ramping and can't take any other stats

[richvacr]

I can figure out how to wire in a multi stage tstat but without the w973 I loose the economizer. Since the greatest use of this unit is spring time in a space with a lot of people the economizer would be a good thing to keep. The other problem is since there is limited use of the room I would like to keep the cost down. Any suggestions

[ascj]

I can figure out how to wire in a multi stage tstat but without the w973 I loose the economizer. Since the greatest use of this unit is spring time in a space with a lot of people the economizer would be a good thing to keep. The other problem is since there is limited use of the room I would like to keep the cost down. Any suggestions

I don't understand the problem. The supply sensor is still available, the logic panel is still available, and the thermostat is still available. Why not just fix it?

[DaveCR]

I think ascj's solution is the least expensive option when you consider the economizer.

If you insist on a traditional thermostat using an economizer package is necessary.
http://customer.honeywell.com/TechLi...0s/63-2576.pdf

My advise to the customer would be along the line of lips' - it's time for a new unit.

[richvacr]

ascj - I have not been back since I got the literature and do not know for sure if the logic panel, tsat/transmitter or sensor is bad. I will go back next week. The room actually has three rtu's all the same and is not being used till the end of the month.

A new unit is a big no.

I would like to know how to update this and the other units contemporary controls that don't cost $800 and can get locally.

[ascj]

ascj - I have not been back since I got the literature and do not know for sure if the logic panel, tsat/transmitter or sensor is bad. I will go back next week. The room actually has three rtu's all the same and is not being used till the end of the month.

A new unit is a big no.

I would like to know how to update this and the other units contemporary controls that don't cost $800 and can get locally.

You can cut all those controls out and put a conventional thermostat in and still use the economizer.

Bad news, it will cost more than replacing a defective part. There is no cheap way out. I have and still work on alot of these systems. The cheaper way out is always the repair of the existing controls. Is is cheap, under $800, mostly no. But it's alot cheaper than the material and labor to try to convert them or replacement of the unit.

Many are afraid of these systems, parts are expensive and they don't understand them. Trying to convert them is as more expensive and requires greater understanding of them.