Wednesday, April 6, 2011

One year wrapup: heating and cooling

In general we love the radiant floor heating system, and the Warmboard definitely seems to be living up to its promises. The tile surfaces are especially consistently comfortable and toasty, while the hardwood areas seem "okay" due to the feeling that the floor temps in those areas have larger temperature swings. I knew beforehand that this was might be an issue, but wanted 3/4" hardwood flooring anyway, and would not change it now even if I could. The hardwood floors and their finish have so far stood up well - I had heard some horror stories about radiant heating ruining the finish.

I went with warmboard over a gypcrete-based solution mainly due to a lot of discussions I saw on the Internet regarding where do you want to store your buffer of heat. With gypcrete-based designs, you store a lot of that heat in the floor; some people advertise this as a good thing but my position is that it's better to keep that heat in your water reservoir until needed (or better yet, forego heating that water at all). Which leads to my next comment which is that our floors & heating system do respond quite rapidly to changes in the thermostat temperatures. Based on subjective feeling, I can sense the changes within ~15 minutes of turning the heat up or down. This was one of the key promises of Warmboard which has been fulfilled imo.

The zone heating is also more effective than I had dared to hope for - I love keeping our master bathroom at ~74-75 deg F, and the master bedroom itself at ~70 deg F - makes nightime bathroom trips quite comfortable. Despite this being "radiant heating", a lot of heat goes up the stairwell and I have only turned on the upstairs heat about three times in the past year (when visiting family came to stay with us). Makes me shake my head - I have a ton of money invested in that upstairs warmboard and the associated radiant plumbing system, and it's hardly getting used! :) Ah well, I still say better safe than sorry.

I have a lingering concern as to whether or not the Unico reverse-cycle chiller is really as economical as advertised - my monthly electric bills have been much higher than expected in cold months. (This may be because I was accustomed to our old house which was 1) smaller and 2) heated with natural gas.) In addition, although quiet the drone of the chiller can get annoying after awhile - a propane-fired primary boiler would have been 100% silent; I also wonder even if we keep the chiller, if a propane-fired backup boiler would have recovered heat more quickly than the electric backup we went with. (As I recall, I wanted to go electric for the most part to obviate the need for periodic propane tank refills.) Finally, I remember the heating company guys saying our chiller was going to be very efficient because it's just barely big enough for the job (3.5 tons). This was supposedly a good thin, but I wonder if that's why it runs so often when it's cold out. At some point I need to figure out how to do an exact cost analysis on my monthly costs.

Still - I'm not going to change out any of these heating system components anytime soon. I am thinking of swapping out the thermostats with some programmable units (normally folks don't bother with those with radiant heating, but I think they would work well with the fast-responding Warmboard).

The system works "pretty well" in air-conditioning mode. There is a huge amount of south-facing wall on this house that acts as a heat sink, and the system operates near continuously on hot summer days. On the hottest days I would have to say that the system is slightly overwhelmed. I think we could improve this by opening some upstairs windows late in the afternoon, to help the system remove much of hot air in the house. An attic-based whole-house fan looks appealing for that same purpose as well.

In retrospect I would have:
1. Located the chiller way over by the garage and far away from living spaces
2. Installed a whole-house attic fan.
3. Gotten more detailed about the system-sizing data to convince myself that the proposed system could handle the heating & cooling load with ease.

1 comment:

  1. Hi Jay,

    I'm curious to get your opinion of warmboard. I am considering the product for many of the reasons you mentioned in previous posts. Do you still have the same sentiment about the inconsistent warmth over your hardwood flooring relative to the tiled areas? Given your experience, is there anything else should be considered?