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6 Answers

Will I be in for a electricity shocker?

Hi everyone,

Based significantly on the guidance from the GBA Website we installed a Fujitsu AGU15RLF, Floor Mount Evaporator and Fujitsu AOU15RLFFH Condenser in our Central Massachusetts 2,200 square foot colonial last week. It is exceeding our expectations one week in with cold and snowy weather.

We bought the house a few months ago and it was heated by electric baseboard we we've moved quickly to take control of the heating bill.

The energy audit identified the insulation as "pretty good" and we had air sealing done the same day.

Asked By Peter Kelly-Joseph | Mar 16 17
8 Answers

Adjusted HRV Calculations

Hi all. I have been looking at options for HRV's for a new, super-insulated home under design. While the Zehnder CA350 would be great, I am pretty sure it may be out of the price range (the exchange rate between US and CAN $ is killing us right now). In my hunt for alternate units using the HVI directory ( for ventilation equipment, I'm finding it challenging because from what I've learned, the HVI uses kind of a bad testing method for equipment, which can often inflate the efficiencies of the units.

Asked By Burke Stoller | Mar 12 17
3 Answers

Does anyone in the Phoenix, AZ area install supply registers in the floor of the main floor?

I am specifically talking about a house with a walk-out basement.

I'll be building a new house with a walk-out basement in the low desert. I'd like my supply registers to NOT be in the attic. Seems nobody wants to do that.

Do floor registers really not work efficiently in the low desert?

Asked By 447debbie | Mar 15 17
1 Answer

Duct Condensation Issue

We moved into our home last year in the middle of summer. At the end of summer, we noticed condensation along one of our HVAC ductwork causing drywall damage in our basement. This ductwork is located in the ceiling in our basement and extends to the register in the bump out in the 1st level of our home.

The bump out is open below and has about a 6 inch gap between bottom of the bump out and ground outside. The bump out has a piece of plywood on the bottom with what appears to be some insulation.

Asked By djm883 | Mar 14 17
11 Answers

Heat-pump water heater for an all-electric garage apartment?

We our building a detached garage w/ 2nd story apartment (1 bedroom, ~900 sq ft conditioned space) & debating the system to heat water:
- Primary purpose for the garage apartment is for our mothers to live in as they age. Mainly for safety reasons, we're not having gas service to the apartment (could do relatively easily - main house has gas service)
- Cooling-dominated climate (Houston TX)

Asked By Robert Hallenbeck | Feb 9 17
8 Answers

How to duct a Whole House Dehumidifier?

I am building a 6000 sq ft house in Alabama. Downstairs is about 4000 of those sq ft. On one of the two A/C units downstairs, we are installing a whole house dehumidifier. My installer will install however I want but he typically pulls air from the return trunk, and returns into the supply trunk bypassing the air handler. Is this the best way to do it?

I've read some prefer to have a dedicated vent in the house to pull in air to WHD and then return to the supply trunk after the air hander. Thanks.

Asked By Richard Marks | Mar 13 17
7 Answers

Mini Split Sizing for cooling and heating

Hi everyone,
I'm new here. I am in the process of planning renovations for a newly acquired home. It's unbelievable how many times I ended up on this site in my quest for information regarding energy efficiency and general best practices, so I thought I should finally join.

As part of the renovations we are planning on installing a mini split heat pump. The primary reason for installing the unit is for conditioning during the summer months; obviously the house already has a heating system (electrical baseboards) but no ac.

Asked By yacpro13 | Mar 9 17
1 Answer

Chiltrix Questions

I'm going to be building a 3000 sq. ft. superinsulated house near Rochester, NY, zone 5. It's a single story with R-40 walls, R-70 roof, and R-20 under the slab. I've had a room-by-room manual J professionally done . The total load for the house is 27914 BTU/h heating at 7F and 18534 BTU/h cooling at 86C.

I'm considering a Chiltrix system. I like the idea of a centralized chiller with fan coils distributed where the loads are. There are hydronic contractors here, so I'm not too worried about the install. I actually ran into a local company with experience with Chiltrix systems.

Asked By John Ranson | Mar 11 17
20 Answers

What kind of chimney for an energy-efficient home?

The recent discussion on masonry heaters in super-insulated homes is great, and Martin's "farewell to the chimney" post is a classic, but I have a question that I don't think has yet been covered here.

I am designing a well-insulated home that will require a modest amount of Btu input that I want to provide with a modest woodstove. What is the best type of chimney to use, masonry or insulated stovepipe? (Or some other option I'm not specifying.)

Asked By Tristan Roberts | Jan 29 11
8 Answers

North Idaho ranch boiler sizing

The plan for the N Idaho ranch is nearing completion. The house will be slab on grade with hydronic floor heat. There will be a natural gas fired boiler supplying heat to the floor tubing and an indirect water heater. Zone 6, heating 1800 sq ft interior plus garage, Attic R 60, Slab R 20, Walls R 23 blown fiberglass, Windows triple pane U .24. My calculations put the design heat loss at 28,000 BTU/hr using outdoor temp of -10F.

Asked By Steve Wolfe | Mar 6 17
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