Community: Mechanicals

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7 Answers

Any hydronic system controls with low standby electricity consumption?

I was feeling good about the changes I'm making to reduce the electricity consumption of my hydronic system: a Grundfos Alpha ECM pump that is consuming only 16 W when it's running, and Taco "sentry" zone valves that use about a watt when on. But I measured the power consumption of controls last night, and it can add up to almost as much as the pump: 3 W for an aquastat, 6 W for a Taco "switching relay" circulator control with one zone on, and 4 W of standby power for the 40 VA 120:24 VAC transformer that powers the zone valves.

Asked By Charlie Sullivan | Sep 2 15
2 Answers

Ducted mini-split serving multiple floors

I am attempting to break my house design into zones such that I can use one mini-split for each zone. I am having trouble simultaneously satisfying two pieces of advice from this forum. In "Rules of Thumb for Ductless Minisplits," Martin says that one ductless head can serve a maximum of about 1100 square feet. That is based on distribution, not capacity. I realize that it is a rule of thumb that might not apply to a super-open floorplan, but if I violate that rule, I should have some justification.

Asked By Reid Baldwin | Sep 2 15
5 Answers

What mechanical system makes the most sense?

I am in a zone 4a Kansas City Missouri. In the heat of the summer it can get up to 95 with high humidity and it doesn't cool down at night.

We are building a 3500sqft ICF house with R-24 walls. (We have the labor and resources for it to be the most affordable option) and a R-60 SIP roof, cathedral ceiling. We are thinking about building with a 4' crawl space, unvented, 20 mil vapor barrier. Our windows and doors we are sourcing from company's in the U.S. which build to the PassivHaus standard.

I have a few questions:

Asked By Jordan Schiele | Sep 2 15
11 Answers

Minisplit or furnace?

Hi, I know there is lots of discussion about this; however, our proposed new construction seems to be in unclear realm of which to use.

Asked By Mark Buckingham | Aug 28 15
17 Answers

Has anyone had experience with the Unico small duct system?

I was looking at the top finishers for the department of energy's "Race to Zero Student Design Competition" ( http://energy.gov/eere/buildings/2015-results ) and found the winner used the Unico system. http://www.unicosystem.com/the-system/how-it-works/air-handlers/. I recall actually being in a home in Chattanooga once 15+ yrs ago that I believe had one of these systems, but I really know nothing about them. With the problems associated with finding small enough systems for well insulated homes and cost effective systems...does anyone know if I should be looking at this as an alternative?

Asked By Andrew Bennett | Apr 29 15
0 Answers

Third-party filters for Zehnder HRV / ERV units?

Besides ordering from zehnder, are there any other filters available that will fit their units? It's not a question of price but more so of long term availability. If they go out of business will I still be able to source filters? I haven't had the chance to pull one out of the packaging and go down to the local HVAC supply house with a tale measure.

I'm an electrician and not an HVAC contractor so I don't understand if these are a common size/shape/build or totally proprietary.

Asked By Lance C | Aug 29 15
7 Answers

Include provision for future ventilation?

The second story of my old farmhouse is gutted. I am in the middle of running electrical, etc and getting ready to close up the walls. It doesn't need it now, but as I keep working, the house may eventually need a ventilation system. Should I include provisions now while the walls are open for a ducted ventilation system later? Is separate ventilation ducting overkill? What type/size of ducting is typically used for the application? Is it best to locate grilles in the floor or walls?

I have done a lot of reading on the topic but I would like some input others.

Asked By Brian C | Aug 21 15
13 Answers

Keeping HVAC inside conditioned space

We have just started construction on my new house. I want to keep the HVAC inside the conditioned space for energy efficiency. The crawlspace will be conditioned and we are using open web floor trusses on the second floor to accommodate the ducts for the second floor.

Asked By Michael Geoghegan | Aug 22 15
6 Answers

"Cycling" ductless mini-split

I'm working on my wife re: her dislike for the appearance of ductless mini-splits, but I have a question regarding their operation.

Asked By Brad VanVickle | Aug 23 15
22 Answers

Is it reasonable to use 3/8" PEX supply lines to all fixtures?

I am planning the plumbing system for my Net-Zero Energy home that is being built to Passive House standards. I will be using PEX tubing with a manifold system using home runs. I designed the house so that the bathrooms and laundry room are centrally located, making the supply runs pretty short. I want to minimize the amount of water and energy being used and low-flow fixtures provide plenty of water for my needs (2.2 gpm at sinks and 2.5 gpm for showers).

Asked By Gerald Blycker | Mar 11 14
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