[Talar]

Hi, I just had some work done to reduce humidity in my home, and the tech lowered the blower speed (under the house) on the hvac unit, and also took some refrigerant out of the outside unit.
Is it normal to reclaim refrigerant when just changing the speed ?

 

[user_12345a]

Blower speed/airflow impacts refrigerant charge for sure - if the charge was checked (superheat/subcool readings among others required, not just pressures) and adjusted correctly, you have nothing to worry about.

 

[Talar]

Thank you for your quick reply. :smile:

 

[bfrabel]

I don't think the 2 things were directly related. I think your refrigerant charge was probably overcharged to begin with.

I say this because slowing down the blower would make the refrigerant pressure lower. You usually wouldn't want to make it even lower than that by removing some of the refrigerant.

I agree with user_12345a that as long as the tech knew what they were doing and got everything adjusted as best as can be, then you are probably good.

 

[user_12345a]

I say this because slowing down the blower would make the refrigerant pressure lower. You usually wouldn't want to make it even lower than that by removing some of the refrigerant.

When there's a fixed orifice, it's important to make sure liquid doesn't return to the compressor and refrigerant may need to be removed after slowing the blower to prevent that and get the sh in the range the manufacturer wants.
equipment is not charged based on pressures.

it is a fine balance because the coil can't be run below freezing - but if there's a risk of freezing at normal return air temperature/load and proper charge though, the blower speed is set too low.

 

[surferdude2]

It sounds like you have a hvac tech that know what to do. Remember him when you have any future problems.

In case you're curious... Fixed flow refrigerant metering devices (which you likely have, as opposed to a thermostatically controlled valve (TXV)) depend on a certain minimum heat load in order to be able to vaporize the liquid refrigerant.

Reducing the air flow changes the effective heat load being brought to the evaporator coil. It may dip to below a load value that the metering device was designed around. The refrigerant may not get vaporized completely before leaving the evaporator coil. (it's called an evaporator coil for a reason) That may make adjustment necessary and more critical than normal in order to avoid flooding liquid refrigerant back to the compressor and possibly liquid slugging it. That can damage a compressor since liquid is very hard to compress and it could also wash the lubricant from critical moving parts.

Now that you know that, you may want to look at the compressor dome after the unit has been running in the low fan mode for an hour to make sure it isn't sweating, which would indicate that even more refrigerant may need to be withdrawn. It's common for the suction line (larger tubing on the compressor) to be cold and even sweat but the compressor body never should.

Sometimes a tech is not able to spend the time to see if his adjustment is perfect, so he'll not mind if you give him a little help or even a call to say he did it perfectly. I often told customers that they can get involved and save both of us some time and money... most liked that concept... especially the money part.

 

[beenthere]

Hi, I just had some work done to reduce humidity in my home, and the tech lowered the blower speed (under the house) on the hvac unit, and also took some refrigerant out of the outside unit.
Is it normal to reclaim refrigerant when just changing the speed ?

It is normal to check the charge.

As for removing refrigerant, depends if its a fixed metering device, and the air flow is lowered too much, and was already low.