This might be a long shot but I thought I'd ask. Our building maintenance department is useless and won't pay to call in an HVAC technician, so they suggested I fix the problem. I don't plan on doing the repair myself, just want to arm myself with some information to bring to the higher ups about this issue. In our area we have a roof top HVAC unit that is pulling room temperature air (19.5 degrees) and is running it through the HVAC unit and dumping it into the room at 11-18 degrees, so needless to say our area is quite cold...to the point of which office staff are closing dampers and plugging the diffusers. Not good, but yet our maintenance department won't do anything about it.
We have a Invensys PEM-1 controller with what is a manual thermostat (which is marked as Sensor RTU-7, top left). The two wires coming from the bottom right, I believe one runs to another manual thermostat as well. Not 100% sure.
What could be done to force the HVAC unit to produce heat? Jumper HT1 to NO3? Can it be disconnected from the ASD bus and have it strictly controlled by the thermostat? Also if it is connected to the ASD bus, can this be remotely controlled by a PC to have a preset temperature that would override the thermostat(s) connected to it?
I don't plan on doing any work to this system, just arming myself with knowledge to bring to the higher ups and possibly offer some troubleshooting advice. The company won't bring in a tech and there is no way else this issue will be resolved. I appreciate any info anyone can provide, my frost bitten hands will thank you!
Wow....Maintenance staff "suggests" you fix it yourself?! I highly recommend you DO NOT take that advice. This is a Network 8000 HVAC control system and not your typical furnace control at home. They are under many names, such Seibe, Barber-Coleman, and ultimately, Invensys. Find out who the local representative is in your area, which I'm assuming is in Canada, based on the Celsius temperature readings you have provided. Politely write a request to your building owner to have them perform a site visit, not to exceed 8 hours, to trouble shoot the matter and possibly improve the situation, or at least, suggest what needs to be done mechanically, if the case necessitates it. Recommend they do this during normal business hours to keep the hourly rate at a minimum.
At 19.5 degrees Celsius, here in the States, that equates to about 67 degrees Fahrenheit for room temperature, which is a bit cold in my opinion for this time as year. However, the building owner sounds a bit on the cheap side, so that could be your culprit there as well. Anyway, having 51 to 64 degree air blowing down on you can be frustrating, but just could be maintaining that low set point. If he or she is aiming for 66 to 68 degrees, (18.9 to 20 degrees Celsius), they might be meeting their mark and to them, nothing is wrong. The energy bill is lower and you are miserable. However, as long as the tenant is paying the rent.........
Best of luck. You are in a tight spot but, if you handle it the right way, just might improve your situation.
"Nearly all men can stand adversity, but if you want to test a man's character, give him power."
-Abraham Lincoln
Whec is right. This probably isn't going to be fixed without a service call to a local rep. But in the short term, to get heat I would pull the wire for the space temp sensor. It will be one of the analog inputs on the left of the picture you posted. This should cause the controller to see a 0 space temp and respond with a heat command. If you still have no heat I would say it's probably not a controller issue and would check the wiring of the unit ventilator.
Wow....Maintenance staff "suggests" you fix it yourself?! I highly recommend you DO NOT take that advice. This is a Network 8000 HVAC control system and not your typical furnace control at home. They are under many names, such Seibe, Barber-Coleman, and ultimately, Invensys. Find out who the local representative is in your area, which I'm assuming is in Canada, based on the Celsius temperature readings you have provided. Politely write a request to your building owner to have them perform a site visit, not to exceed 8 hours, to trouble shoot the matter and possibly improve the situation, or at least, suggest what needs to be done mechanically, if the case necessitates it. Recommend they do this during normal business hours to keep the hourly rate at a minimum.
At 19.5 degrees Celsius, here in the States, that equates to about 67 degrees Fahrenheit for room temperature, which is a bit cold in my opinion for this time as year. However, the building owner sounds a bit on the cheap side, so that could be your culprit there as well. Anyway, having 51 to 64 degree air blowing down on you can be frustrating, but just could be maintaining that low set point. If he or she is aiming for 66 to 68 degrees, (18.9 to 20 degrees Celsius), they might be meeting their mark and to them, nothing is wrong. The energy bill is lower and you are miserable. However, as long as the tenant is paying the rent.........
Best of luck. You are in a tight spot but, if you handle it the right way, just might improve your situation.
Thank you so much for your response. I think the fix it yourself response was the hope that I'd just play with the thermostats and nothing would happen beyond that. I have had both thermostats turned up to 30deg C over the weekend and come back into the office with the exact same temperature in our office area, 19.5deg C range. The crazy part is that the building we occupy probably has 10 rooftop HVAC units and the area outside of ours is a nice 23-24 degree range, so it's not the maintenance department trying to save cost on energy bills. It's just a lack of effort or sabotage? Haha.
I can't post a link but I did find a brief manual online about the controller and with your info about it being a networked unit (ASD bus), could this just be controlled by a PC to disregard the thermostat inputs and just use the thermostats for monitoring only? So ultimately the maintenance department could just define the temperature and the thermostats wouldn't be able to actually affect anything?
Originally Posted by BrianWithAnI
Whec is right. This probably isn't going to be fixed without a service call to a local rep. But in the short term, to get heat I would pull the wire for the space temp sensor. It will be one of the analog inputs on the left of the picture you posted. This should cause the controller to see a 0 space temp and respond with a heat command. If you still have no heat I would say it's probably not a controller issue and would check the wiring of the unit ventilator.
So disconnecting the thermostat will cause the controller to call for heat? Any particular wire I should disconnect to check? The "Sensor RTU-7" is connected to SP+, AS1, COM and AT1. Does it even look like there is a second thermostat connected to the PEM-1 unit? I could see about simply disconnecting the entire thermostat itself too as the thermostat is much more accessible than the
The "Sensor RTU-7" is a TAC TSMN-90250-850-0-1, it has a manual slide for temperature setting as well as an occupancy button (a house with a person located inside of it). Is the occupancy button an overide? I'm not sure.
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Originally Posted by whec720
