Several years ago we built a 16 x 24 foot addition off the back of our house. In Connecticut. Cathedral ceiling, mostly glass (Pella – don’t ever do that!) over a crawl space. Crawl space had 6″ fiberglass batts installed but a collection of mice invaded and took most of it down. They’re pretty much dead now, but it won’t be till the spring before I get in there to clean it out and get foam sprayed in the floor cavities.
Heating for the first floor is one continuous baseboard loop starting in a LR, through a small bath, into the basement to go under kitchen cabinets till pipe goes out into addition around all walls, down into the crawl space, then back into the main basement till it comes up in a DR, heads through the remainder of the LR and back down to the boiler.
In the winter, that addition gets mighty cold at night and just saps whatever heat the boiler is putting out so that the water is lukewarm by the time it gets back into the main part of the house. Initial heat up to temperature can take 2 hours in January/February. With the price of fuel oil probably at $2.25 a gallon, I’m thinking of short-circuiting the addition and only heating the main portion of the house. We only use the addition 2 maybe 3 times during the winter, and it can be sealed off from the house pretty efficiently. In retrospect, although it looks great it was not a wise investment.
Query: If I modify the pipes on the existing zone so that hot water merely circulates to radiators in the main part of the house, that will make my use of the heat in that water more efficient – it will more quickly heat up the part of the house we actually live in, are getting dressed in, showered in, etc.
But, then what are my options for heating the addition?
A) Install a separate zone to be turned on only when needed? Can I trust antifreeze in the boiler water so it won’t freeze and burst a radiator pipe? Can it sit like that, with water/antifreeze in the pipes, from start of heating season till Thanksgiving, and then off again till Christmas/New Years, and then off again till Spring without serious risk of damage? (No other water pipes in addition to worry about).
B) Install a separate zone for the addition but keep that loop drained and fill it only when it is to be used, again draining it in between uses? If so, should I install some kind of an air vent somewhere in that loop to make sure I get all the boiler water out of the pipes? (Unless some product is specifically made for this purpose, I was thinking a “T” replacing an elbow where it returns under the floor and top it with a normal water valve – either specifically for a boiler or for an outside faucet). Do I have to bleed the system on refill or is that something modern systems automatically do? Would/could that same air vent double as a bleed vent?
C) Tear it all out and replace it with electric baseboard heat (probably with some supplemental heaters to keep it warm) and just bite the electrical $ bullet those few times we actually used the addition? Not to mention the cost of installing the wiring from the CB panel 50-60′ away. I don’t really like this idea – for one the installation cost would be huge, and the per usage cost would also be huge.
D) Someone else have any better idea? No, wife refuses to even entertain idea of wood/coal/kerosene/propane stove. The room looks like something out of Good Housekeeping magazine and an auxiliary stove just does not fit into her concept. Me? Vermont Castings all the way! Right beneath my gun rack next to my trophy heads – 2 squirrels and a chipmunk.
Thanks.
Replies
Where to start? When hydronic heat is installed properly, there is nothing better. When it is installed badly, there is nothing worse.
First, if the return temps are low enough, usually less than 135, your boiler is probably dying.
In addition, the water is probably too cool by the last set of baseboards for the amount of baseboard.
If the basement is open, I would look at zoning each room or area seperately.
Use a header in the basement,P/S to protect the boiler and pex feeding each zone.
Outdoor reset to save fuel, and your wife should be happy too.
I think you should find a good hydronics installer that knows how to do a heat loss and knows baseboard. Probably cheaper than buying a new boiler.
Edited 10/1/2005 10:45 am ET by rich1
Boiler is not more than 10 years old. Installed by the oil company that's been supplying oil to our family for decades. I presumed they were competent.
Not sure what the return temp of the water is, although I think it would vary. At the beginning of the heating cycle when the morning heat up cycle kicks in, most of the heat is going to be removed from the water and put into the air and the temperature of the returning water will be cool. Later, as the air in the rooms heats up and the differential isn't that great, the returning temp should be warmer. Yes?
Different zones is fine, but I'm worried about freezing radiator pipes during extended periods of non-use in a closed off room.
Can I rely on the antifreeze to protect me or should I drain and refill the pipes in that zone? If drain/refill, do I need to bleed to fill and vent to empty?
BTW, what's an outdoor reset? And "P/S to protect the boiler" means what?
Thanks.Griff
The return temps need to be measured, and they are probably worse on the coldest day of the year.
If you do close off the sunroom, you will need to drain or add glycol if there is a chance of freezing. Both have pros and cons. Draining and adding water is generally considered hard on a system. Every time you add water you add O2, which is not good on a system.
Zoning the system would probably allow you to heat the sunroom, but it is hard to say for sure without being onsite. It also allows you to heat only the rooms that need heating.
Basically P/S is primary/ secondary, where one piping loop is the boiler loop with it's own pump, and the zones are seperate, taking only what they need. This allows the boiler to be protected by having enough flow. It can get more complicated than that, but that's the short version.
Outdoor reset measures the outdoor temps and resets the boiler supply temp. On the coldest day of the year, you will probably need 180. As it gets warmer outside, you can lower the supply temp within the limits of your system. The rule of thumb is for every 3 degrees you can lower the supply temp, you save 1% on fuel costs.
Edited 10/1/2005 3:28 pm ET by rich1
You're on the right track, so allow me to just add a couple more things to think about.
The boiler company may have installed the proper boiler for the home way back when it was built. The current setup doesn't sound proper anymore, something that can happen in the heat of battle as the addition is roughed in.
As a start, have a look over at the homeowner resources at buildingscience.com. I would follow their advice and put down a vapor barrier, then 2"+ of XPS insulation, and then hermetically seal the crawlspace. That should increase your comfort, reduce humidity, and reduce heat losses. It might even help keep the vermin out.
I would put the sunroom on its own hydronic loop. The delta-T you're describing will quickly kill a boiler unless it is protected by primary-secondary piping, or if it can take advantage of low return water temperatures (Viessmann Vitola, Buderus G215, for example).
Furthermore, the reason the addition does not heat properly may be related to the supply temperature of the water by the time it reaches the addition. In order to get up to temperature faster than within 2 hours, it may need hotter water than the loop can currently supply. In other words, the supply piping may be what's preventing your emitters from working properly, not the boiler.
Thus I would do the following: At the very least, I would make the sunroom its own zone. You could put a thermostat in there that keeps it at 50°F and avoid the headaches associated with glycol. If you really want the anti-freeze protection, I would fit a flat-plate heat exchanger in the basement, and only anti-freeze the circuit actually in the sunroom. Glycol loops need monitoring as the antifreeze can turn acidic over time and turn your piping/emitters into swiss cheese.
Due to the oxygen-related corrosion of heating systems, I would also dissuade you from filling the loops as needed. Keeping the room at 50°F is much easier.
And To Rich1 (hope that's for real), too.
Thanks for the responses guys. You answered my questions to the extent that I know what I'm going to have done.
First to correct an omission on my part - the sun room was built before the hydronic system was installed, so it was supposed to be part of the heating equation.
I'll have the sunroom separated off into it's own zone with it's own thermostat and keep it, as suggested, around 50 degrees (thermostats go that low?). Well, whatever minimum is without shutting off the flow. Guess I'll have to put the ceiling fan on slow reverse on a timer so the hot air gets recirculated back down to the thermostat. Maybe there's even a way to have it come on when the circulating pump is on for that zone - I'll have to speak with an electrician about that. Otherwise, I'll be wasting a lot of heat for nothing. Maybe someone ought to invent retractable shutters to pull across the ceiling and eliminate the cathedral part to contain the hot air - wouldn't have much insulation value, but it would seem to be better than nothing.
The first floor as its own zone will be much smaller and much more efficiently heated without the drain of the sun room. And, I'd been postponing it, but I'll have PEX run up to the second floor and heat put in up there too - I have some construction going on in the first floor bath and with the open walls am easily able to have the vertical PEX runs made within 15' of the boiler.
Lastly, I like the thought of the outdoor reset, so I'll see if it can be retrofitted onto my boiler. The boiler is along an exterior wall in the basement, so getting access to the outside should be relatively easy.
Yessir, thanks guys. Very informative help.Griff