HVAC / Condo Question
I'm looking for a third (or beyond) opinion on the HVAC Unit in my condo. I live in a ten story building that has a central source of heating and cooling, but an individual heat exchanger in each unit. The heat pump within my unit has stopped working four times during the year that I've owned the unit. It stopped working once over the summer during a particularly hot spell - the fan would blow, but no cooling was happening. An HVAC tech came and adjusted the pressure (he said that the pressure was too high, and that was tripping a safety shutoff in the unit) - he stated that the problem was with the cold water supply from the building, not my individual unit, and that it was bound to stop working again. Around a month later, it did stop working again and an HVAC tech working on behalf of my building made some adjustments to the central heating/cooling system and my unit then resumed operation.
Everything was fine until around two weeks ago, when the unit (trying to heat this time) once again stopped working. The same HVAC tech working on behalf of my building came back and "flushed the system" and "added more coolant" (those are both my wife's words - I was not home at the time) and the system started working again, but he said that the unit was "too big for our condo" and should be replaced with a smaller unit.
Everything worked fine again for about two weeks, and then on Friday the unit stopped working again. Again, the unit would blow around air but it would not actually heat any of it. On Saturday, it would heat our condo to around 62 degrees and then the heating functionality would stop. Today, it is working fine (note that the exterior temperature has risen in the meantime) and will heat our condo to the normal temperature.
We have another tech (someone who we have called, not someone working on behalf of our condo) coming tomorrow to examine the system. Although it's working fine at this point, I have little doubt that it will conk out again next time it gets cold. My questions:
- The tech working on behalf of our building claims that the problem is with our unit, whereas the tech who came on our behalf claimed the problem was with the building. What sort of questions do I need to ask to determine what the real problem is?
- Is it realistic that the unit is "too big" for our condo? I'm going to go to the other owners with our sized condo tomorrow to see what they have - but it worked fine all last winter, so I find this explanation suspect.
- Is there anything else that I should know about this type of setup?
Thanks in advance for the help - I am fine with replacing the unit if it truly is defective, but I suspect the issue lies with the building and I'm not sure how to address this.
Have any of the other people in the building had the same issue? Is it the original unit that was installed when condo was built?
Why would a unit that was enginneered for the buildings water supply and heat loss and gain be the wrong size. I am assuming that this is an original unit. What is the age of the unit and age of the condo? It sounds as though you may have an heat exchanger problem or a motor problem. We need more info for sure.
Ask your neighbors to see if the problem is building wide or is it local to you?
I wamder if the pressure reducing valve/ fill valve is allowing too much pressure into the loop and causing the pressure switch on the circulating pumps to trip causing the whole loop to lose water flow.
TO really diagnose it, we would need water temperatures, flow, air tempratures, and ideally unit pressures.
Simple things to check are for clean air filter.
I'm wondering if the building has a cooling tower and the chemicals are not being maintained, fouling your heat exchanger or as mentioned above, their circulation pumps are shutting down.
Remember, they must provide treated cooling water at the proper flow rate and within a reasonable temrpature range (60-90F summer, 40-70F winter) Outside of those approximate range, you may have issues esepcailly if you have low flow.