Friday, April 19, 2013

Why doesn't it get warm downstairs in the winter?

So I heard from neighbors they couldn't get their homes warm downstairs. The funny thing about this is that it isn't a secret in the building community that three story, and greater, town homes have issues with temp distribution. The four story units have a split heating system to help cope with this issue.

So Pulte decided to put in a zoned system to help the three story town homes improve the temp distribution. I got curious, just how bad was the temp spread?  I picked up 6 Temp and Humidity data loggers to find out.

What I found is in the graph below. Pulte's temp warranty specification is 4 degrees Fahrenheit between rooms and floors (Section 23.2). My favorite part of the discussion with Pulte was them telling me that it's 4 degrees between adjacent floors, so theoretically it could be 72 on the third floor and 64 on the ground floor, and that would meet the design specification. Yeah, that makes sense, you want it 68 downstairs... how about 76 upstairs?

For this data set, the thermostat was located in the hallway on the second floor in the original design position and set to 68 degrees. You can see the temp spread was anywhere from 3-7 degrees from the kitchen to the third floor rec room.

Click on it to make it full sized.
I'm happy to provide the data file if you're interested.

Pulte's answer to this was to put in two zones to reduce temperature variation in the home. In their infinite wisdom, they chose to put in two zones. The third floor is its own zone, and the first and second floor are the other zone together. I particularly loved that the construction folks played the upgrade to the zoned system as a complimentary upgrade to "do the right thing", when per the terms of their warranty, they had to fix it.

Now you may be thinking, perhaps three zones is too complex substantially more expensive... Nah, they put in a three zone controller board (HZ322) made by Honeywell. They just couldn't be bothered to put the zone dampers anywhere but in the mechanical room. You might also be wondering how they put in new thermostats. They just used the RedLINK wireless ones, so they didn't have to put in a thermostat wire to the downstairs. You know, because nobody would want a Nest wired thermostat.

What happened with two zones? The thermostat downstairs tried to heat the downstairs to 68 degrees, and the concrete slab is a big heat sink, so it ran a lot. This dumped lots of heat into the master bedroom, and then up the stairs to the rec room. I sat in bed sweating for 2 nights before I decided that enough was enough, and I'd put in the proper installation of one zone per floor that I asked them to do in the first place.

I'll detail the install in a future post, but I will say the temp is now consistent around the house. Now that we're in Air Conditioning season, it's great to be able to turn down the temp in just the master bedroom, and have the system really only worry about the third floor heat load.

So, Pulte, thanks for the zone controller board and the dampers for the third floor. Too bad we couldn't have had it done right the first time. Pulte - Life Tested!

1 comment:

  1. Hi, so did you end up having two or three zones? And how did you get Pulte to do it? I want to make the same request but I just want to know what I should say so they don't try to dodge it like they always do with everything else. Thanks so much for posting all this information!

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