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4 Answers

New Mitsubishi Hyper Heat multi splits have finally arrived

I was having a discussion with someone on reddit and they mentioned having a MXZ-3C24NAHZ model recommended by a contractor, which I had never seen before. Googled it and, lo and behold, I find documents published just a couple months ago (like this one) describing a whole new line of Hyper Heat multi splits, sized from 20,000 BTU/hr through 48,000, and supporting 2 to 8 indoor units. HSPF rating is generally in the 9 to 11 range.

Asked By Nick Welch | Jan 13 15
9 Answers

Seasonal humidity and lack of outside airflow

Hello,

Asked By Geoff York | Mar 2 15
4 Answers

Sealed crawl with passive exhaust?

I work with a non-profit building small, affordable houses in climate zone 4A. We have tried a few different methods of sealed/ conditioned crawls, but I am interested in finding the best, inexpensive method that will work long term for our buyers. So it needs to require minimal to zero maintenance or understanding of the science behind it for the people living in the house.

Asked By Emily Lingerfelt | Mar 3 15
9 Answers

Why is it so trendy to hate on radiant in-floor heat?

I recently built a 2000 square foot house in climate zone 7. The building is two stories on a slab heated by a Navien 240a combination boiler. There is no heat source on the second story, and the simple system has only one zone, which is all it needs because all the rooms in the house stay at the same temperature--maybe it's a few degrees cooler in the upstairs bedrooms if the doors are shut for 24 hours or more. I spent just over five grand on the heating system--installed--although I got a tankless water heater in the process, so the real cost was more like $3500. How is that overkill?

Asked By Josh Jipson | Mar 1 15
17 Answers

Recommendation for minisplits vs. gas-fired HVAC for new Massachusetts building

I am building an energy efficient 15 unit apartment building in MA this spring. We can either go natural gas or electric. I am considering going all electric since the MA Energy Code is so stringent and the heat load will be relatively small even though there are very cold temps at times. We might even put on solar panels for the house meter.
The electric units would take up much less space and I would rather not have to put in gas at all. I am not thrilled about electric hot water heaters but understand that the newer tankless units are much better.
Any input would be appreciated.

Asked By Bill Perkins | Feb 25 15
15 Answers

Wood floor underlayment over radiant heated floor

Hi,

I am building a 2 story house wood frame house(with basement) that is heated with radiant hot water system installed in the floor.

The joists have been blown in with loose fill cellulose (for both sound and to keep the heat up) and a plywood floor is on top of the joists. R5 foam board is installed on top of the plywood and the PEX tubes are installed to the foam board. They will be pouring a self leveling concrete on top of the PEX and then gluing down engineered wood floors.

Asked By Howard Klein | Mar 5 14
6 Answers

Running PEX in-floor in addition to baseboard

I'm building a new wood frame home with hot water baseboard heating in climate zone 6. The bathroom will have tile floors and I was thinking of using some electric resistance heat under the tile along with a baseboard hot water radiator in the bathroom. These electric systems are not inexpensive to install or operate so I am now considering simply running loops of Pex (the supply line to the bathroom radiator) between the joists to keep the tiles warm before the water in the line gets to the baseboard radiator.

Asked By George LaLonde | Mar 2 15
4 Answers

Multi split with ceiling fans?

I am looking into a multisplit heat pump system for our deep energy retrofit project. We are used to leaky homes with ceiling fans in all bedrooms while sleeping. We find the moving air to be very comfortable while sleeping. In fact we noticeably miss the fans when traveling even when there is a dedicated Hvac like in a hotel room. In general, is the modern usage of the term 'comfort' (meaning stable temperature and humidity) consistent with our desire to feel the lightly moving air when sleeping?

Asked By alok khuntia | Feb 27 15
6 Answers

Air-source heat pump vs. AC/furnace

I am contemplating some different HVAC options in Connecticut (zone 5). I currently have an 80% efficiency Carrier Infinity NG furnace (8 years old) that can be paired with a Carrier Greenspeed heat pump. I can do that for $11,400 before incentives, or replace my existing and dying 10 SEER AC unit with a new 16 SEER for $8,000.

Asked By Anthony Kane | Feb 24 15
2 Answers

Load rating for 2x4 by 2x6 post

We are adding a second floor over living area, the room size is 35' x 18.5'. We have divided the room into three sections with a two support beams in middle of the 18.5' section. What would the load rating be for the post if it is made of 2- 2x4 and 2- 2x6 hollow middle?

Asked By Tim Eicher | Feb 24 15
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