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Bob_M
Anon
2014-Dec-19 10:57 am
[HVAC] Connect heat and AC to same furnace blower speedMy house in winter is more comfortable when I move the blower to high. I want to keep the blower at high in summer. Is there a way of having the heat and AC use the same fan speed? |
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neonhomerDearborn 5-2750 Premium Member join:2004-01-27 Edgewater, FL |
neonhomer
Premium Member
2014-Dec-19 11:04 am
Most AC systems are charged with the evaporator fan set at a certain speed. Changing the fan speed can affect how well the unit preforms. |
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garys_2k Premium Member join:2004-05-07 Farmington, MI |
to Bob_M
Splice both of the wires together so they both connect to the same motor tap. |
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OldCableGuy3
Anon
2014-Dec-19 11:56 am
There are also "blade splitters" that allow you to connect the leads to the splitter and then the splitter to the blade without having to splice. This allows you to move it back easier if it causes trouble. I believe I found one at Autozone for under a buck, but don't quote me. |
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Sly Premium Member join:2004-02-20 Tennessee 1 edit |
Sly to Bob_M
Premium Member
2014-Dec-19 1:43 pm
to Bob_M
If you run the system on high in the winter time then you may end up using more electricity. Not only is the fan running higher which draws more current, but it can also cool down the indoor coil more (remove more heat). While this may at first seem like a good thing in that you are extracting more heat from your system, it can also mean that you are returning less heat to your outside unit. This can add more subcooling to your refrigerant and cause your outside evaporator to run colder. This can create more icing on the outdoor coil and cause the system to have to defrost more often (assuming you have a demand defrost system).
However if you want to take your chances and run the system with 2 different speeds, you could use a 24v AC relay. You have to know how your system is wired... either your (O)range or (B)lue wire is energized whenever the system is in heating. Find the wire on the thermostat that has 24volts AC whenever you are in heating mode and splice it into coil side of the relay. Unplug the wire that you are using to switch blower speed and hook it to the source for the switching side of the relay. Now connect two wires to the blower from the relay. One wire will be normally closed, the other normally open. Now whenever the system is in cooling, it will energize the medium or low fan speed (depending on what you have) and when it is in heating it will energize the relay and power the fan through the high side.
If you are unsure of how to wire relays then do not attempt this. If you wire it wrong you could short out your thermostat to line voltage and possibly cause a fire. You could also electrocute yourself. Attempt only if you know what you are doing.
[edit] You don't want to increase your fan speed in the summer. The fan is set that way for a reason. Typically the fan will run slower to allow the coil to cool down more, removing humidity from your air. If you increase the fan speed in the summer then you will not remove as much humidity. The house will feel warmer which will cause you to set the thermostat lower and use more electricity. Also with higher humidity you may get mold growth in your walls and in your HVAC system. It needs to be set lower when in AC mode. Don't change it... |
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jrs8084 Premium Member join:2002-03-02 Statesville, NC |
jrs8084
Premium Member
2014-Dec-19 2:04 pm
I must have missed where the OP said he or she had a heat pump. |
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Sly Premium Member join:2004-02-20 Tennessee |
Sly
Premium Member
2014-Dec-19 2:09 pm
Either way it still stands. You don't want to increase the fan speed in the summer which is what the OP was wanting do to. Heat pump or AC, both need a lower fan speed to remove humidity. |
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Bob_M to Sly
Anon
2014-Dec-19 2:12 pm
to Sly
Thanks Sly. I don't have a heat pump. I have a conventional natural gas furnace with AC. I want to keep my AC on high speed blower, and just move my heat to high speeds blower also. |
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robbin Mod join:2000-09-21 Leander, TX |
to Bob_M
I want to try to clarify the OPs question. Normally, heat uses a low to medium fan blower speed. AC normally uses a high fan speed. So what the OP is proposing is to increase the fan speed of the heat cycle while leaving the cooling as it is. Is this correct OP? If so, then as mentioned above, you simply splice the wires or best is to use a terminal piggyback. This kit is gives a few extra pieces but has what you need » www.amazon.com/Dorman-HE ··· 00CO99H4You will use either one of the double male piggybacks or double male chairs depending on space on the circuit board. The only concern I would have is you need to keep the furnace in it's proper temperature range if it's gas or you will probably loose efficiency. There should be info on your furnace giving a range of the heat rise that the furnace is designed for. Lets say it's 50 to 90 degrees -- measure the return air temp and add the lower number and that is the lowest temp that the air should be exiting the furnace. You use those numbers when installing a furnace to select the proper air speed. |
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to Bob_M
Have you checked the furnace board and instructions? I have a Trane forced air furnace with DC blower, XV90 2000-vintage, and it allows me to set DIP switches for heat and A/C blower speeds. Seems to me the manual has some tables for setting CFM based on static pressure.
Right though, settings are not the same. The reason I was looking at this was that the "fan" setting is relatively low and I was looking to increase that in the summer. |
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TexDave's not here Premium Member join:2012-10-20 |
Tex to Bob_M
Premium Member
2014-Dec-19 7:17 pm
to Bob_M
said by Bob_M :My house in winter is more comfortable when I move the blower to high. I want to keep the blower at high in summer. Is there a way of having the heat and AC use the same fan speed? So, you assume, because your house is more comfortable in the winter when the blower runs at high speed in the heating mode, that the house is going to be more comfortable in the summer when the blower runs at high speed in the cooling mode? If that's your thinking, my personal opinion is you should probably not be jacking with your system. |
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