Woodburning stove in new home construction

[Chillimau]

Pat,

Do you remember the brand of the stoves with the "donut" or high mount storage?

Any thoughts about supplementing a hydronic system with solar hot water? With the warm winter we have had so far a boiler might not need to be fired very often.

[Leef]

Thanks Pat,

My intuition was that venting the combustion chamber of the stove was necessary, but I didn't know if the HRV would compensate. Your explanation makes sense.

If I remember right you used Simonton windows in your home right? Here in Iowa, Pella Windows are used and the builder is familiar with them. I recently found a local seller of Simonton, Marvin, and Anderson. Are the vinyl Simonton windows any different to install? In a 2x6" wall we would need some sort of jam extender - since the windows are not wood, I presume a drywall "return" could work fine.

Your window advice has been very thorough. I have just shopped and looked for price and "Energy Star Rated". If they are Energy Star rated, I've assumed that they are a good choice. Is that too simplistic?

Maybe I should start a new thread for our new home construction. We're supposed to break ground end of March or early April.

Leef

[Pat]

Chillimau, I don't recall the brand names. One of the resources that I saw, if I remember correctly, was an extensive marine catalog. It had diesel stoves, both natural draft and blower type as well as all sorts of STUFF, including doughnut shaped water tanks that fit around the flue pipe of some of the stoves. Some were specific to a brrand/model while others were "after market" so to speak.

Like I said before, in-floor hydronics doesn't care how you get the hot water just that you do get the hot water. It would be pretty straight forward to use a standard solar water heating design intended for DHW to make hot water for hydronic heat. Instead of drawing off hot water with a faucet instead you would circulate the hot water through the radiant panel(s) in your hydronic system.

I once did some preliminary design work on a thermosyphon approach to hydronic heat. I had in mind our Mexican "solar only" development in Baja California. The idea was to reduce or elliminate the need for electricity. If the solar collectors are mounted physically lower than the radiant panel (wall, floor, or ceiling with hydronic heat tubing) then the difference in density of the supply vs the return water will drive the circulation.

Water heated by the solar panel rises to the radiant panel and the cooler water (after giving up heat to the panel) falls back down to the solar panel. If you are in an area where it freezes then use anti-freeze in the water as the collectors can get quite cool at night. A check valve makes sure the water starts up in the right direction. As with solar heat for DHW, you can have gas backup or whatever. Some solar systems only preheat the water and don't get hot enough for DHW but reduce the cost of DHW. Same story with solar hydronics.

There is a tendency with our weather vagaries (Oklahoma) to have a couple really cold days, single digits or zero, then have an afternoon in the 60's or higher within a day or so. The typical hydronic system will run hard to try to hold the room temp as the heat losses escolate, driven by the large delta T as temps fall... and then with the slab heated nicely and producing the required Btu's to hold temp the outside temp hits the 60's or more and the space is over heated. There is quite a lag/phase shift in hydronically heated slabs. The time constant is quite large.

There are a couple ways to take this problem down a notch or two. 1. Reduce the thermal mass and or 2. don't derive all the space's heat requirement from hydronics. In method 1 you can use in-ceiling hydronics. Sheetrock over the PEX tubing has a much lower thermal mass than a concrete slab. It can track the changing conditions a lot faster. For number 2 you can run the floors enough to be comfortable but not supply all the heat required. You can supplement with a heat source that can be shut down quickly. The combination of hydronics (to make the floor comfortable and make a more comfortable radiant environment) and another heat source like a pellet stove, gas log, forced air, or whatever works well. When the demand goes down like during a hot afternoon you just shut down the supplemental heat as required. A T-stat will automate this.

I use both of these methods. My geo heat pump can make hot water, hot air, or both at the same time. There are pairs of thermostats in some of the major zones. One controls the hydronics and the other controls the forced air. You can put the forced air into a night time "set back" mode and let the room temp fall several degrees say to 60 F and the floor will be warmed as required to hold 60. The next morning the programable T-stat turns on the forced air to bing the space up to your desired daytime temp, say 73. The floors are still warm, just not so warm they will overheat the space if the outside temp rises quickly.

Three of my rooms have radiant ceilings, i.e. PEX in the ceiling under the sheetrock. They are quite comfortable and respond faster to changing ambient conditions. Two of the rooms got radiant ceilings because they "fell in a crack" and the HVAC outfit forgot to include them in the design and added them on late in the game when I found the oversight. I designed the master bedroom to have radiant ceilings and it works well. The radiation from the ceiling beams down and warms the carpet and tile so the floors aren't so cool as with forced air. The tile is not as warm as say the bathroom with its radiant floors but it is not unpleasant like it would be with forced air.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[Pat]

Leef, If I recall properly (and I think I do) Pella windows would have cost about $30,000 more than the Simonton and Atrium brands that I used. Simonton has different quality levels and I went for the higher rated units. The price diff was based on the GOOD Simontons. I have been extremely pleased with warranty service from Simonton. One window just cracked for no apparent reason and the "guts" were replaced after warranty expired with no hassle. A couple others had minor air leaks. All were repaired expeditiously. Some plastic welding debris had to be trimmed. I have no problem recommending Simonton.

Energy Star rating is good but I definitely would NOT rely only on that rating and price. All Energy Star windows are NOT created equal. You want to compare the performance specs. What U value do you get? What % transmission of visible light do you want? Low E? How low? Learn what the figures of merit are, what they mean, and what the importance of each is to you in your application. If you do this you will probably not buy Pella. They are heavilly advertised but don't out perform other well engineered but less heavily advertised brands.

My master bedroom has 8 inch concrete walls with 2 1/2 inches of styrofoam on both sides then drywall on inside and vinyl and brick on the outside. I have drywall "returns" and they look OK. The basement windows are in 12 inch thick concrete walls plus vinyl siding and will have cedar trim inside. They look a tad deep but are still OK.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]