Community: Mechanicals

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7 Answers

Duct cleaning and sealing

Much of our Zone 1 (basement and first floor) ductwork has been in a vented, unconditioned crawlspace for 70 years. The ducts are galvanized steel, and condensation marks are evident on their exterior. The placement of supplies and registers can also be improved in several rooms. Two well-regarded HVAC pros eyeballed the ducts and recommended keeping most of it, although a third stated that the more we can replace, the better. Tearing the galvanized ducts from ceilings and walls and replacing them would be a major project.

Asked By Emerson | Dec 23 17
14 Answers

ERV or HRV (yes, bringing it up again)

I've read all the articles and posts I can find on here about this question, and if anything I feel less able to make this choice than before. So many conflicting opinions. Here are the factors that affect the decision, as far as I can surmise:
-predominantly heating climate, but mixed and with hot, humid summers (SW Ontario) <-points to ERV?
-medium sized house? 2430 square feet, no basement
-3-4 occupants, higher than average humidity generation (not a lot of showers, but lots of cooking/baking - think 1950s housewife levels, then add some more) <-points to HRV?

Asked By Trevor Lambert | Feb 27 18
14 Answers

Mitsubishi Slim Duct (SEZ) in unconditioned attic?

I live in a two story colonial with an unfinished attic (insulation on attic floor) in NJ. The house has a single zone 2.5 ton A/C that does not sufficiently cool the 2nd floor. All 3 bedrooms are upstairs. We typically set the thermostat to 67F in July/August. That's the only way to get the upstairs somewhat tolerable (<75F).

Had a HVAC contractor over and he suggested two Mitsubishi slim duct (SEZ-KD12NA4R1.TH) installed in the attic. One to serve the master BR and the other one to serve both kids rooms. It would be connected to a multi outdoor unit (MXZ-2C20NAHZ2 or MXZ-3C24NAHZ2).

Asked By Inverter0815 | Mar 2 18
16 Answers

Tankless backup for a heat-pump water heater

I currently have a GE Geospring 50 gal heat pump water heater (now discontinued) that has worked pretty well. However, my toddler will be using more hot water as she ages and we're finishing the basement to rent out, most likely to one person. Lately, the water heater has been maxing out after two showers (2.5 GPM x 10 min x 2 people=50 gal). I'll be retrofitting a 1.5 gpm adapter which will help, but I'm still nervous about having a tenant and running out of hot water.

Asked By Pat Beurskens | Feb 26 18
5 Answers

Mitsubishi minisplit secret advanced settings

This is more an invitation to share than a question per se. I recently installed a two-zone Mitsubishi minisplit system in our home. One of the two indoor units is ducted and its blower continued to run even after the temperature set point had been reached. I understand this is normal operation for these units (and maybe for all/most minisplits?). I also realize there is a reasonable to case to be made to run the fan continuously even when heat/coolth is not being provided. However, I didn't want the fan when the heat/cooling is not on.

Asked By Chris Stratton | Feb 20 18
12 Answers

Ultimate Air vs. Zehnder HRV

I recall seeing in the comments for the article discussing a new way to duct hrv's that one of the Zehnder reps was disparaging the Stirling Technologies Recoupaerator 200dx for having something to the effect of misleading, incorrect, etc. performance numbers and that it does not stack up to Zehnders products. I was wondering if that rep and anyone else could clarify why the Zehnder product would be better than the 200dx and how they differ in function? The cost of the 200dx is significantly less.

Asked By Spencer Burnfield | Sep 4 12
5 Answers

Dehumidification and (or vs.) mini-splits

I'm in Austin TX. We have significant humidity, including in "shoulder" seasons where cooling is not really needed but dehumidification is. Probably the worst times are when the day is hot and humid, but the night is cold, condensation on windows is a major problem all over the city. No one likes running the AC to super chill just to dehumidify.

So the smart recommendation is a dedicated dehumidifier, like the Ultra-Aire series. Ok, costs a bit more than AC only but everyone says they are great.

Asked By James Howison | Feb 22 18
1 Answer

Midea Ductless Units

In our full-house renovation, we have decided to replace the oil furnace with a series of mini splits throughout the house. We have met with multiple HVAC contractors to price the project, and were/are planning on going with the Mitsubishi product, until recently when one HVAC installer (who also installs Mitsubishi) recommended Midea. This was the first time I've heard of this brand and a cursory search on the internet doesn't show a significant US market share.

Asked By Ryan Wiley | Feb 22 18
3 Answers
5 Answers

Branch box location question

Branch Box for Mini-split system serving upstairs living quarters. The manufacturer says: don't install in a hot and humid location for long periods of time. They also say: Branch Box is indoor use only. I'm in CZ 3, central Oklahoma. Can I put this in an attic in my location? I would say no. Should I try to get it inside a mechanical room location down on the first floor(near 1st floor ceiling/2nd floor floor)? I would still have to run all the branch lines through the floor and up the walls to the attic and then to the air handler locations.

Asked By Inger Peters | Oct 27 17
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