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8 Answers

Radon mitigation and fresh air supply combined?

Hello, if a home tests positive for radon and also would like to have an ERV & fresh air ventilation system, can these things be combined? In other words, can I tie a subslab depressurization system into a the ERV and fresh air system? Alternatively, is there any evidence that a moderate radon problem (4.1) can be mitigated with fresh air ventilation only?

In Green building techniques | Asked By Ryan Griffin | Jan 12 15
2 Answers

Cathedral attic moisture

I have an attic converted to living space where the roof is also the cathedral ceiling. Most bays go from soffit to ridge and are insulated with fiberglass and a foil barrier with a Duravent installed so that there is always an airspace from soffit to ridge. Those bays are mostly fine. The areas I'm having a ton of ice and moisture on the sheathing is where the bays are interrupted and there is only a ridge vent. Should I fill the bays solid with spray foam? Or should I at least foam up the ridge vent from the inside on those bays?

In GBA Pro help | Asked By steven pereira | Jan 13 15
6 Answers

Closing vents in unused rooms

My local utility had the following info on it's web site regarding closing vents in unused rooms. Any contrary thoughts on this?

"It’s true that closing a vent or two may reduce the furnace’s efficiency slightly. But if you’re closing a vent to avoid heating an area that doesn’t need to be heated, the energy you save will be greater than the energy lost due to the slight increase in inefficiency.

Bottom line: If you don’t need to heat a room, close the vents in that room."

In Mechanicals | Asked By Stephen Martinson | Jan 5 15
12 Answers

To insulate pipes or not to insulate pipes (hot water radiators)

I live in a 145+ year old house in NJ. I have 2 boilers in an uninsulated basement with 5 zones plus an indirect water heater, 4 zones are hot water radiators & 1 is radiant floor heat. There are about 14 big cast iron radiators in the house which is to say a lot of pipe running all around the basement of different sizes and material (mostly copper also black pipe, galvanized ?) The reason I mention all the zones is because each one has its own pump and different run of pipes to illustrate how much copper we are talking about.

In General questions | Asked By Dan N | Jan 8 15
1 Answer

Two layers of R4.2 on attic ductwork

Hello all,

A client just had her ducts insulated. Unfortunately, the HVAC company installed R4.2 instead of R8 and to 'ease' the repair just wrapped another layer of R4.2 over the existing layer. Now I'm concerned about condensation or vapor lock here in Chicago (hot summers and cold winters). Should I/we be concerned and should it be fixed or is the risk relatively low? The ducts are rigid and mastic-ed at every junction. Thanks...Ross

In Mechanicals | Asked By Ross Neag | Jan 12 15
2 Answers

Insulating Rim Joists on 100 y/o balloon framed home

Long time lurker here. I have air leaks at my rim joist and planned on using rigid foam and spray foam to seal them up. Previous owner had put insulation batts in the space, and when I peeled a section up, I realized that my home is balloon framed. Now I'm not sure how to proceed, and if I even should. I am considering using Great Stuff and just sealing around the bottom of the rim joist and putting the batts back in place.

In Energy efficiency and durability | Asked By Ric Pasqua | Jan 11 15
2 Answers

Can I use two layers of Tyvek in a wall assembly without moisture problems?

I am building a house which has a REMOTE wall system in it (foam "outsulation"). Although I passed on the relevant information to the builder, who is usually on top of the details, he managed to mess up with the window bucks.

The wall structure is 2x4 studs (with R13 cavity insulation), plywood sheathing, Tyvek Drain Wrap (wrinkled stuff) 2 layers of EPS foam of R10 each sealed with Siga Wigluv tape, then 3/4" plywood furring strips followed by wood siding.

In Green building techniques | Asked By Gary Dick | Jan 11 15
15 Answers

Log home insulation advice...

My son has a 1990 built log home (from a kit) in climate zone 6. He has been there 2 winters, and although a nice house we are dealing with the energy issues inherent in this design. We have done small things like basement and rim joist insulation, caulking, etc, and have bigger plans for the future (about which I have gotten good advice from this site) when finances allow.

In Energy efficiency and durability | Asked By Howard Gentler | Jan 8 15
4 Answers

Poured-In foam for retrofit insulation of cathedral ceiling

I have a cathedral ceiling with pickled boards. The previous owner insulated the 2x8 rafters with fiberglass and vent baffles to the ridge vent, which means about 6" of insulation. I'm trying to avoid removing all the boards to insulate. At the top of the ceiling is a horizontal area of about 3 feet wide. If I remove just those horizontal boards (and the soffits) I have access to the cavities.

In Energy efficiency and durability | Asked By Ed Dooley | Jan 11 15
3 Answers

Heat pump COP vs. capacity

A while back Marc Rosenbaum mentioned tuning his heat pump to more closely track the needed capacity in heating mode, and reported significant efficiency improvement. I dug into the documentation for the Daikin here and while it doesn't really have truly *variable* capacity in heating mode -- it tends to just run full-blast because there's no issue about latent load -- it does have a "demand" setting which simply reduces the output to a configurable percentage. This is either a fixed setting or can be externally switched in and out via wired control from, say, a building-management system.

In Mechanicals | Asked By Hobbit _ | Jan 8 15
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