HVAC Questions? Ask an HVAC Expert for Answers ASAP
This building has 125 apartments with about 400 McQuay units. Only this one unit is causing a problem. Can't get to name plate on tower at this point in the evening. Can check tomorrow. I think it is a closed system but can't say for sure. I have three. They are 18,000 BTU units (largest). The units were put in 10/28/09 in my apartment; not even four years yet. Entire system and all units, no more than 10 years old. I replaced these for higher efficiency and look but turned out to not be a good idea.
Enfinity units cause problems that older Mcquay units do not and unfortunately, I'm one with the new units. We stopped putting these in and no longer recommend Enfinity. Even more modern versions of the older models cause no problems. To us, Enfinity is a lemon. The third unit in my apartment came with a refrigeration leak and had to be fixed in warranty. 100% failure not a good track record and failures not field fixable from what I can tell.
Maybe history on one that acted the same is useful but it may not be same problem. I no longer trust the high pressure relay. Warranty fixed once on one unit, broken again in the same unit, 1 year later. That unit got to point where it wouldn't even come on in both failures. It has been bypassed since end of February though I do want to replace the relay this summer. This second unit is starting to behave the same way though not yet just stopping immediately. The second unit now fails about one minute into operation, maybe a little longer.
The relay is a simple thing to find but I don't think it can be replaced without draining refrigerant. It's inexpensive. Is that what you would think as well about replacement?
Since I seem to have this problem off and on and repairs don't come fast; parts take a little while for Enfinity, when you say 1 in 10, is it only a damage possibility or is there actual danger from bypassing? I know you can only guess. I just have no feel at all; the other one has been without the high pressure control in operation since end of February.
You are right; it's easy to lose patience on this kind of problem especially when the new units seem to be unreliable.
Hello again Dan.Just to clarify, myself nor Just Answer has any affiliation to McQuay at all, any information or view points you get from me is entirely unbiased. I have no ax to grind with McQuay and no need at all to defend any of their products.The latest models of many products these days have problems due to the heavy reliance on Chinese made electronics components...those have not been the most reliable in the world.. some of these new units have four (4) micro computers on board..with dozens of frail wire connections. I avoid them at all costs. However these days there are often no other options. What exactly is going on with your units remains to be discovered.Regarding the 1 in 10 immediate risk of running the system without a high pressure switch... if it loses cooling water it will overheat and possibly blow the soft plug and release all of the refrigerant, then it is possible that the compressor will keep running without refrigerant in it and burn out. As long it has cooling water it will most likely be OK however.McQuay is an old line company with a decent reputation, recently bought out by Daikin Kogyo Company in Japan, 2 years ago I believe, (one of the worlds largest refrigeration and air conditioning equipment manufacturers with very high standards). There is no telling whats going on with the 3 you bought however.I would hazard a guess that the technician that recharged one of them with refrigerant failed to evacuate the air out of it before recharging, or over charged the unit slightly and that would definitely cause the problem you are having with the pressure switch... getting the refrigerant charge right is as much of an art as a science.. it takes some experience that person may or may not have had... We can do some tests. You will need a thermometer, a cheap one will work just fine.Run each of your units in cooling mode for 5 minutes set at maximum cooling, fans on high speed.... and measure the difference between the cold air blowing out and the air going into the unit at the bottom...that will tell me if one of the units is over charged or not.Lets see how that goes.Phil
Phil, Thanks for the info and I'll definitely be giving you a high rating. I wish I were able to find a technician that would listen to me that well here but maybe I'll be lucky. Let me return to where I was and ask these questions briefly. I guess that close to the threshold part is not giving the units as good a reputation as might have been desired.
1. On the unit where we bypassed it and it kept cutting off, do you think it could be the sensor? That was its original problem. That unit is showing those perfect differentials now. That would mean replacing a sensor and not the refrigerant pressure approach. I haven't put that sensor back into the system yet. It is running without a high pressure sensor; for past 3+ months. Sensor possibly?
2. Does the refrigerant pressure modifications work as well in reducing problems in heating as cooling?
3. Am I correct in saying that the sensor can't easily be replaced in the field? I think the system has to be drained; maybe more for all I know. Manhattan is not a joy for moving equipment in and out and they aren't light.
4. I'm tempted to bypass the sensor on the down one as was done to the other one. The other unit seems to have worked fine despite the risk with perfect differentials. Really bad idea? Moderately bad idea? Somewhat bad idea? Etc. Is there a physical danger to this (no I won't come back and said you said something) or just a damage risk?
Phil, I noticed this and not sure it is what you meant to say:
"If it runs those 29-26F differentials then it is most likely not getting the cooling water it needs... there may or may not be a valve in the water line that can be adjusted to give that unit more flow... an experienced technician can look that over and tell you what options you have." Since you said they were optimal temperatures, maybe you meant different values if it "is not getting what is needed."
OK, I got it. Now, I'm feeling I'm taking too much of your time but I did find out two other things that may be of value. Also, I just want to see if I have any protection from the suction line temperature sensor. I didn't see a low pressure sensor. Getting a little nervous about the one without a high pressure sensor (not this one; the other unit that is working without it). Not happy with bulding technician not getting back and replacing switch (if it is switch). I have a grand piano next to it!
On new findings, we had a high flow problem in building (not temperature) though as usual, I'm first to go. It eventually shut down all my units, even one with high pressure sensor removed. We fixed it this afternoon and the two others came back on. This unit didn't. For this unit, I took off cover and sides including filter. It ran with everything off. Then, I added the sides, then the cover, then the filter, checking it each time. It runs each time. Unclear why this would make it work (though I think doing it changes pressure)?? This allowed me to get temperature differential. It might be slighlty overcharged??
It is 73.6 to 49.2. 24.4 degrees (with filter, 1/2 inch quited)
It is 74.2 to 53.1 21.1 degrees
To be sure, I would have refrigerant drained if you think that will make it less finicky. Regularly breaking is unpleasnt, especially in winter. Even as head of the board, fixing the building for a couple units will be hard. I've toyed with replacing them because of this. I rarely have cooling problems; it's usually in winter.
I have no feel for how much time you should spend on a question. If you would like me to ask the above separately to get you some additional $, I will not feel bad and I'm not testing you to see what you will say. I might need you again with these units. The other unit remains for me to work on before I call McQuay. I hate to say it but in NYC, I've found I've needed to know as much as the technicians before they come on these units. I'm not sure the problem with that unit is the sensor but I've not had time to look at it. But, it has no high pressure protection as of today!
Hello again, the fact that removing the doors and replacing them allowed the unit to work, indicates that the door switch was not tripped, panel replaced slightly off last time, not closing the door safety switch... and this time you fit the door properly.Or... there is a loose wire inside that got jiggled ... if there is no door switch look for loose wire connection problems... you will however most likely find a door switch (on the service panel frame) ____________
The suction line low temperature cut out switch will not suffice for a low pressure cut out switch in the event the refrigerant charge is lost.
With the filter in place there is slightly less air flow so the coil runs cooler and increases the temperature differential. (a person has to think about that for a while until it makes sense, its a worthwhile insight ) ________You can find a good technician by first understanding that chart and my comments, then grill the potential new tech on it... if he is sharp it will go well.
These pressures vary with fan speed as well so a balance has to be achieved that will not allow the coil to ice at low fan speeds and not be too high at high speeds.
The factory weighs the charge in to solve that problem... tweeking the system by letting an ounce or two of gas out is bit of an art..
Your most recent remarks indicate that there are underlying problems with the liquid cooler.... it may not be properly maintained, the spray nozzles inside need to be kept clean along with the suction filters on the pumps... and elsewhere in the system. If that doesn't solve the problems, then a larger pump might solve the problem. I would focus on that aspect heavily. _____The bonus button comes up only after you rate positively... let me know how that goes I will appreciate it!... at times the bonus's don't show up.. lost in space or something.. the servers can have bugs etcYou can stay in touch even after you rate, on the same dime so to speak for a while.Phil