Circulation

[esteslaw]

I have a big vaulted room facing south, and get a lot of solar gain in summer and winter. Main living space is lower level; a balcony and bedroom up get uncomfortably warm before thermostat (downstairs) calls for AC. Is it possible to have someone put a thermostat upstairs to activate fan only at certain temp; and continue to allow main level thermostat to control call for heat/cool? It seems like this would be a good solution as the upper thermostat would cause the warm air to recirculate through the house keeping temp consistent throughout; then the main thermostat can turn on the ac when the whole house temp gets high ???

[skippedover]

A separate t-stat, while possible, would be overkill, IMO. Why not just select the fan to the 'ON' mode rather than 'Auto'?

[beenthere]

Many newer thermostats have a circ feature. That automatically runs the fan if no call for heat has happened in X minutes.

[beachtech]

Running continious fan in the summer, will actually turn your AC system into a humidifier.

Sounds to me like your floor plan is in dire need of a zone system and some duct modifications.

[skippedover]

Running continious fan in the summer, will actually turn your AC system into a humidifier.

Sounds to me like your floor plan is in dire need of a zone system and some duct modifications.

Your statement is a little misleading and borders on a scare tactic. When the AC turns off and the coil is still dripping wet, some of that moisture will re-evaporate into the room air if the blower is on during that time for sure. This will raise the humidity level from where it was at the end of the AC cooling cycle but only on the order of a few per cent points. Furthermore, most new t-stats today actually recognize this feature and will cycle the blower off for a pre-determined time, usually 2 to 5 minutes and then restart it. But it does NOT make the AC operate as a humidifier. That's just simply misleading.

I do agree that a zone control system would be ideal but it would likely be an expensive and involved process to be done properly. There's much more to it than just putting in some dampers if it's to be done properly so I didn't visit that topic.

[thermojohn]

If the ducts are outside the conditioned envolope, it's not too good of an idea to run the blower continuously due to possible duct leaks / infiltration and if in a hot attic, heat exchanger effect, heating up the air in the conditoned space.

I rarely recommend operating the blower continuously. The problem should be solved by zoning. Rooms with high solar gain will never remain stabilized when comparing them to the main 'core' of the rest of the home or business. Put the conditioned air where it needs it when it needs it. Zoning is the way to go with this.

Yes, it's costly, but what is the cost if it is not done?

[TwincamDave]

My first question is , is there a "return" up stairs? If not it could be as simple as adding one provided you have access to do so.

[skippedover]

If the ducts are outside the conditioned envolope, it's not too good of an idea to run the blower continuously due to possible duct leaks / infiltration and if in a hot attic, heat exchanger effect, heating up the air in the conditoned space.

I rarely recommend operating the blower continuously. The problem should be solved by zoning. Rooms with high solar gain will never remain stabilized when comparing them to the main 'core' of the rest of the home or business. Put the conditioned air where it needs it when it needs it. Zoning is the way to go with this.

Yes, it's costly, but what is the cost if it is not done?

If your ducts leak, seal them. There are tests for that very purpose. Good insulation on the attic ducts should eliminate a lot of heat exchanger effect, especially when the condenser isn't running. Remember, heat flows from warmer to cooler and the greater the temperature difference, the faster it flows. Thus, 73°F air being circulated through a 135°F attic will exchange less Btu's than 55°F air in the same attic. And when all is said and done, comfort for the home's occupants trumps a small loss of efficiency, IMO.

[beachtech]

Your statement is a little misleading and borders on a scare tactic. When the AC turns off and the coil is still dripping wet, some of that moisture will re-evaporate into the room air if the blower is on during that time for sure. This will raise the humidity level from where it was at the end of the AC cooling cycle but only on the order of a few per cent points. Furthermore, most new t-stats today actually recognize this feature and will cycle the blower off for a pre-determined time, usually 2 to 5 minutes and then restart it. But it does NOT make the AC operate as a humidifier. That's just simply misleading.

I do agree that a zone control system would be ideal but it would likely be an expensive and involved process to be done properly. There's much more to it than just putting in some dampers if it's to be done properly so I didn't visit that topic.

my statement is true. not misleading at all. ESPECIALLY, if the system is horizontally installed :)

if you'd like to take a trip down here and spend a few days, i'll be more than happy to show it to you :)

[skippedover]

Well if it is in fact true in your area, it's not in mine. Therefore, the statement cannot be made as a blanket effect. I fail to understand how a unit that is simply circulating interior air can actually increase the humidity level in the home (absent leaky ducts) above that which would occur otherwise with the unit off. Perhaps you can educate me?

[tipsrfine]

I asked a similar question as the OP here before and was told that there are t-stats that have the capability of having a zone senser connected to it. I agree with the OP that this would be good sollution. The t-stat can be programmed to turn on the "fan" only when the zone senser indicates the zoned area has climbed above the temp where the t-stat is located. This is a much better sollution than the "fan on" continuously. The t-stat can still control when the air conditioning is turned on.

[tinknocker service tech]

why not just move the tstat and ballance the system first