Mitsubishi ducted minisplit air handler in unconditioned attic. Will it be a problem in the winter?

newtonkid88

I just had a ducted Mitsubishi Hyper Heat minisplit system installed. The air handler is in the unconditioned attic. 

Will it be an issue in the wintertime because of the condensate drain and trap? It will probably freeze?

Located in Massachusetts

Thank you

EdTheHeaterMan

That has been known to happen. You can do several things to prevent that from happening.

1. At the end of the cooling season have the drain trap blown out to be sure there is no water to freeze
2. make sure the condensation drain is below the insulation that keeps the warm inside the home from leaking out to the attic. That means the drain trap needs to be installed in such a way that the trap is close to the ceiling and has insulation above it. (this may be a problem if the fittings fail and leak on the ceiling below)
3. Add heat tape to the drain line. properly installed and insulated this option can be safe. (improper installation could heat buildup that can cause a fire)
4. The safest thing is to build a removable insulated enclosure that fits over the air handler where the drain pipes are. This will trap heat from the room below, inside the enclosure to keep that area from getting below freezing.
5. I had my attic ceiling professionally insulated with spray foam. This made the attic much warmer in the winter and much cooler in the summer. Solving the freezing problem and reduced the cost of heating and cooling


There really is no easy way to solve this.

newtonkid88

EdTheHeaterMan said:

That has been known to happen. You can do several things to prevent that from happening. 1. At the end of the cooling season have the drain trap blown out to be sure there is no water to freeze 2. make sure the condensation drain is below the insulation that keeps the warm inside the home from leaking out to the attic. That means the drain trap needs to be installed in such a way that the trap is close to the ceiling and has insulation above it. (this may be a problem if the fittings fail and leak on the ceiling below) 3. Add heat tape to the drain line. properly installed and insulated this option can be safe. (improper installation could heat buildup that can cause a fire) 4. The safest thing is to build a removable insulated enclosure that fits over the air handler where the drain pipes are. This will trap heat from the room below, inside the enclosure to keep that area from getting below freezing. 5. I had my attic ceiling professionally insulated with spray foam. This made the attic much warmer in the winter and much cooler in the summer. Solving the freezing problem and reduced the cost of heating and cooling There really is no easy way to solve this.

1) Is this necessary if I will continue to use the HVAC in the winter, in heat mode? Will it still create condensation in heat mode?

2) I can reinstall the drain piping.

3) Im gonna stay away from heat tape.

4) My roof is really low.The rafters are about 2” away from the top of the air handler.

thank you!

WMno57

newtonkid88 said:

1) Is this necessary if I will continue to use the HVAC in the winter, in heat mode? Will it still create condensation in heat mode?

The trap is not the only problem.
In winter the air handler will draw warm humid air from your house. This will create condensation when the warm humid conditioned space air comes in contact with any surface that is below the dew point of the air. The condensation will drip on the insulation, ceiling drywall, wherever gravity takes it.
I once installed a bathroom fan that caused me no end of problems with condensation. It even dripped condensation on the bathroom floor when the fan wasn't being used. Air sealing, insulation, and good flapper doors on the air inlets should in theory prevent this. In reality, they don't. Ironically the bathroom had a window, it didn't need a fan. I should have never cut that hole in the drywall ceiling which is a better vapor barrier than anything else.
I think your heat pump is best used as a Summer AC only. Empty the trap every fall. Crawling through your attic will get old as you get older. I'm not familiar with the Mitsubishi Hyper Heat. Could the trap be bypassed and/or relocated to conditioned space?
The contractor who installed this should be sent to a re-education camp for a week in Siberia.