Attic with heat pump insulation options

[thammel]

Not the garage but the house. Our house has one of the heat pumps in the attic. There is blown in insulation there. I'd love to make it a conditioned space to greatly ease the load on the heat pump. The options I see are :

1) open cell spray foam on the underside of the roof sheathing. Is it necessary or advisable to remove all the blown in insulation?
1a) could staple poly air flow baffles from eaves to ridge and spray foam over them....advisable or not?

2) attach foam boards over the 2x4 trusses to leave air flow channels from eave to ridge.

I prefer #2 but may be tough to find anyone to do this and I don't think I want to do it myself.

Comments? Experience either way?
Thanks,
Tom

 

[thammel]

Any comment on the above? Has anyone had foam blown onto the underside of their attic sheathing to create a conditioned space? Any concerns about the life of the roof shingles? Or any mold concerns?

 

[Jeepster04]

Is the heat pump actually in the attic? Not just the air handler?

I've seen picture of this but kinda thought it was a joke. Insulating the attic wont do much but you need as much air flow as possible...

 

[larry4406]

I don’t have any experience with conditioned attic conversions like that.

I read about it briefly and saw the same concerns as you and stopped.

What level of insulation do you currently have? I’m guessing R30? Maybe overblowing it R60 would help. Obviously you still need to keep the unit accessible.

 

[ericm]

Is the heat pump actually in the attic? Not just the air handler?

That would be nuts. No one does that, do they?


I assumed it's just the air handler in the attic. In that case the heat in the attic is not going to affect it much. But have the ducting in the attic checked for leaks and missing insulation. Duct insulation is usually pretty bad when it's installed, and then later it falls off.

 

[thammel]

Yes, the air handler/evaporator is in the attic. Compressor is outside. Ductwork is in the attic. Blown in insulation is in the attic at about 10" depth. I've checked and repaired with HVAC metal tape any possible leaky areas in the ducts. My concern is the summer/winter temps that are fighting (i.e. opposite) the hvac system temps. And of course, those temperature conditions can't be good for the air handler in the attic.

I'm shooting to improve the thermal efficiency in my house. The motivation is a new law in MD that has driven away ALL competition from BGE (baltimore gas and electric). This just happened this month. Previously, we could search and select from various electricity suppliers. I was paying 0.0949$/kwh. Now we are all at the mercy of BGE and the rate is 0.1295/KWH. Something like a 32% increase. The lobbyists must have been paid by BGE to get this law enacted. Grrr. This state is getting crazy expensive. A new law also increased car registration. Used to be $90/year. Now it's $192 for one year.

 

[billconner]

Spray roof deck with closed cell foam - at least 1 to 1 1/2" in your area. Then open cell if you want but should be code R value, I think R49 for ceilings in Baltimore.

 

[75gmck25]

I am in Alexandria, VA and we had the underside of our roof deck spray-foamed when we renovated a few years ago. Southland Insulators used Icynene open cell foam and it's about 10" thick (but I would have to check the receipt to verify). The air handler and ducts for our A/C are in the attic, so now they are in conditioned space. We have had no issues, and the attic temp is never more than a few degrees different than the temp in the 2nd floor. I've worked up there in both summer and winter to balance out air flow and check the A/C, and it's not uncomfortable.

We also had them remove all the loose insulation in the 2nd floor ceiling, since it was old rock wool that was incredibly dusty. We only use the attic unit for A/C, since we have hydronic radiator heat.

 

[larry4406]

I am in Alexandria, VA and we had the underside of our roof deck spray-foamed when we renovated a few years ago. Southland Insulators used Icynene open cell foam and it's about 10" thick (but I would have to check the receipt to verify). The air handler and ducts for our A/C are in the attic, so now they are in conditioned space. We have had no issues, and the attic temp is never more than a few degrees different than the temp in the 2nd floor. I've worked up there in both summer and winter to balance out air flow and check the A/C, and it's not uncomfortable.

We also had them remove all the loose insulation in the 2nd floor ceiling, since it was old rock wool that was incredibly dusty. We only use the attic unit for A/C, since we have hydronic radiator heat.

When they did this, did they seal your soffit vents and ridge vent closed?

Did you actually add an HVAC supply register to the attic to "condition" it or is it just leakage thru the now drywall only between the 2nd floor and attic space?

Southland Insulators is a good outfit. They have a sister division in Maryland, Devere Insulation that is also very good.