Community: Mechanicals

Q & A Instructions

[Click map to enlarge]

The web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, the usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration: Under the box labeled “More explanation,” look for the words “File attachments.” Click that, and you should be able to attach a photo.

Thanks for joining the conversation!

3 Answers

Pros/Cons of upgrading to 5 stage heat pump from 1 stage?

My residence currently has a Carrier 1-stage heat pump system. Other HVAC components include: LifeBreath HRV195 balanced airflow ventilation unit; Honeywell DR120 bypass return air DEhumidifier; and a bypass activated carbon & HEPA air filtration unit. Each of those components have their own integral 1-speed air fan. Dealing with the different cfm created by each of those components makes it a challenge for my HVAC service company to achieve "balanced" airflow for the HRV and keeping the HVAC system static pressure within specifications.

Asked By Terry Sopher Sr | Jun 28 17
6 Answers

What is minisplit short cycling? Turndown?

I understand that a "somewhat" oversized mini split will generally run at a more efficient rate, as opposed to an undersized mini split, which will run full-out, and therefore be less efficient. It sounds as if the problems with oversized mini splits would be 1) wasted money on oversize equipment, and 2) decreased dehumidification, due to the equipment not running enough. Am I about right, so far?

Asked By Ben Rush | Jun 25 17
9 Answers

HRV for wet room exhaust: Will I have to build a motorized damper box myself?

I currently own a 2006 Lifebreath HRV 155cfm unit in SouthWestern Ontario. It was ducted well enough, but it basically pulls from too many areas of the house (kitchen, laundry room, 3 bathrooms). It does a good job of whole house ventilation, but basically it feels underpowered for wet room exhaust (1850sqft 2 story, with unit in basement, so some runs are also quite long, all flex).

Asked By Mai Tai | Feb 8 17
10 Answers

Panasonic WhisperValue DC fan and TRB transfer box - anyone using these in the field yet?

For a while now I've been considering different ideas to distribute the air from my mini split to bedrooms when the doors are closed. I just noticed that Panasonic recently came out with a new DC motor version of their 3 3/8" deep WhisperValue fan, with selectable speeds (50/80/100CFM) and pretty low sone (noise) ratings.

They also make this transfer box that's designed to fit this fan (google Panasonic TRB -- I can't link anything or the spam filter gets me).

Asked By Nick Welch | Jun 27 17
3 Answers

ERV odour?

I've read of issues of some ERV units having a "plasticky" stink, as discussed on some austrian and german forums, which affects certain batches of enthalpy heat exchangers made by paul, and used by zehnder and helios among others.

But that aside, how would an ERV cope with removing odours made by regular but moderte cooking?

For example, we stir fry vegetables and grill meat maybe twice a week rest of the time it's just pasta or eggs or some soups.

Equivalent of climate zone 4 (~philladelphia), 3 people in a new 2200sqft house.

Asked By davor radman | Jun 28 17
2 Answers

Non-electric Fresh Air vents

I am considering using the Lunos type of ventilation fans which seem to require electricity all the time in order to work. Has anyone used these non-electric ventilation devices?

This is for an off grid cabin run on PV panels.

Asked By Scott Wilson | Jun 27 17
13 Answers

Drainwater heat recovery questions

Hello, I've been reading some things on drainwater heat recovery and came upon this article:

In it, Lyndon Than says, "Leave at least a 12-inch run of straight drain pipe above the exchanger to smooth out the flow."

How critical is that? I don't have.much room to work with -- about 36" in total. I could likely get a 30" unit in that space, but if the 12" above is necessary, it wouldn't be worth the trouble.

Asked By Calum Wilde | Jun 26 17
8 Answers

Which ductless minisplit?

Zone 4 climate - 735 sqft - R25 walls - R40 roof - R5 windows - very tight ICF home - glazing is minimal with a low SHGC

A Manual J was done and it showed a 1 ton unit would heat/cool the home. I'm undecided if I should bump up to a 1.5 ton unit? Here are my options:

A - DuctlessAire Mini-Split - 1.5 ton - 21.0 SEER - $1,400
B - DuctlessAire Mini-Split - 1 ton - 21.5 SEER $1,060

Is it worth the extra $340 to up-size to the 1.5 ton unit?

Asked By Peter L | Jun 22 17
6 Answers

Considering ERV pre-heating options (maybe cooling too)

Hello from a long-time lurker but first-time poster!

It's hard to express how helpful and inspiring this website is to a non-professional like myself. I'm particularly taken by the generosity of spirit shown by all who contribute thoughts, ideas, and experience with such passion. It seems that everyone wants to do their part to help heal our hurting planet--buildings are a huge part. Thank you, thank you.

Okay...end of speech. Some details about our build plans.

Asked By Richard Hoenich | Jun 24 17
3 Answers

Are Blueridge mini-splits any good?

Hi All,
Does anyone have any experience with Blueridge mini-splits? They seem to be the house brand of Alpine Home Air. Any idea who makes them? Are they any good?

Asked By Ben Rush | Jun 20 17
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!