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5 Answers

Islandable battery bank box venting options

Anyone out there have experience with battery bank ventilation in a tight house?

We're building a PGH in Climate Zone 4A. It's designed for net-zero, so we'll have a 6 kW grid-tied PV system. It will also have islanding capability (provided by a dedicated inverter and 12 kVA battery bank).

Based on a rough blower door test we are < 0.6 ACH50.

The battery bank will sit in the basement, which is conditioned space. I want to make sure we are venting the battery box in a safe and effective manner. As I see the issue:

It must vent hydrogen gas effectively
It must not backdraft

In Mechanicals | Asked By Daniel Ernst | Oct 12 14
13 Answers

Space and water heating for a micro-load house

I've been re-reading Martin Holladay's posts on water heating as I once again deal with a small-ish super-efficient house: 1900 ft2 with a heating load of less than 20 kBtu/hour. The homeowners have access to propane and electricity and here in MN, electricity is still generated by a lot of coal, although the homeowners are planning for a pv system.

At the moment I've narrowed heat/hot water system ideas down to three:
1. use a 6kW modulating electric boiler for space heat (hydronic radiant) and also to fire to an indirect tank for hot water. Also, use a drainwater heat recovery device.

In Mechanicals | Asked By Rachel Wagner | May 14 13
7 Answers

Does this plan for a vented over-roof make sense?

Hi all, first time asking a question but I’ve found this Q&A very helpful in the past. Thanks in advance for your help.

I’m planning to add a vented over-roof to my zone 6 northern NY house. It has three roof sections: two cathedral and one with an attic. I’ll be dense packing the cathedral ceilings with cellulose and spray foaming the attic before over-roofing, making all three roofs hot and roughly R-25+ before the over-roof. Here’s the thinking on the vented over-roof layers, from bottom up:

1) Decking
2) Air barrier membrane

In Plans Review | Asked By Jan Wellford | Oct 3 14
5 Answers

Does the Air Scrubber Plus need the fan on continuously to work properly?

I had the Air Scrubber Plus installed on my central unit. I understand the fan helps the product purify the air. I'm concerned the fan will burnout if it is on all the time. Can you tell me if I need to leave the fan on 24/7 to support the product? If do, will continuous blowing damage the fan?

In General questions | Asked By Ann Cobb | Oct 11 14
7 Answers

Outdoor catalytic wood stove: smoke reduction devices

Hi all,

We have an outdoor catalytic wood stove with an 8-inch pipe, and our neighbors want us to cut down the amount of smoke. It sometimes drifts over in their direction... We live in the Northeast US and it's starting to get cold around here!

We found this Catalytic Add-on Stove Damper online:


In Green products and materials | Asked By Alex Forbes | Oct 13 14
2 Answers

Bathroom venting concerns

I have a 2 story/2-unit balloon-frame building from 1929, plus a hip roof. The 1st and 2nd floor bathrooms are on top of each other on the back center of the building. Both have fans, but neither vent to the outside!! We have mold/moisture concerns in the back rooms of the house. No wonder.

Venting each fan has a separate issue.

In General questions | Asked By A. Bradford | Oct 12 14
6 Answers

How do I cost effectively insulate the ceilings of my detached garage?

I have a 22x22 detached garage with a 15x15 addition on the back (both gable roofs) that I'm turning into a shop. I live in Iowa and have run a gas line to it and have purchased a gas heater capable of heating. I would like to heat the garage at low heat and will crank it for shop time. Each space has 2x4 rafters, but no insulation, no ridge vent or other roof venting and only one of the two spaces allows free flowing air to enter the building through the rafters running beyond the building envelope as the 22x space has wood blocking.

In Energy efficiency and durability | Asked By Matt McDevitt | Oct 12 14
9 Answers

How can I attach a ledger to an outside brick wall for a deck?

How can I attach a ledger to an outside brick wall for a deck when foam is used on the outside of sheathing?

I have 3 inches of foam then a 1 nice air gap, and I need advice on how to attach the ledger.

In GBA Pro help | Asked By michael kasales | Oct 9 14
5 Answers

Truly "smart" thermostats and boiler controllers?

Well, my new boiler is in (a Lochinvar WHN-85, with a Lochinvar SIT 40 indirect water heater). As far as I can tell this early in the season it's working fine. But, I've been thinking about my thermostats and how they communicate with the boiler, and wondering if there might be a better way.

My old boiler was a standard dumb boiler. Each circulator was on if its thermostat was calling for heat, and the boiler was on (full blast) if a circulator was on and the water temp wasn't at the limit. True bang-bang control.

In Mechanicals | Asked By Daniel Griscom | Oct 11 14
13 Answers

Should my indirect hot water heater have a mixing valve?

I have a 2300 square foot colonial, built 1960 in Massachusetts (Zone 5A), with three zones of fin tube baseboard. There's a 75 gallon whirlpool tub which we almost never use; the two showers are fairly low-flow. Heat loss done by Comfort-Calc.net was 55,840. I use town water, which is very good quality (Quabbin reservoir). I've accepted a bid to replace my heating system with a Lochinvar WHN-85 boiler and SIT40 indirect water heater.

In Mechanicals | Asked By Daniel Griscom | Sep 15 14
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