I had my house built last year. I opted for LP due to the ease of one fuel, gen set is LP, and we wanted a gas cooktop.
After this heating season I’m not so sure I made the proper choice. System 2000, 2100 sq ft of heated space, 10 ft ceilings mostly except cathedral for 1/2 the 2nd floor. House is well built and insulated FG walls 6″, 16″ in the half the 2nd floor ceiling (flat) and 8″ FG with foil face 1-1/2 rigid on the angled ceiling for the balance. 5 heating zones. All interior walls are 4″ FG. There is very little ice (near nothing)formation on the drip edge. Yes there are a few windows. Used the FP once. Used the woodstove once. We have not insulated the first floor joists. Yet.
Boiler short cycles it’s burn time. Not long fires but a bunch of short ones. I have a System 2000 here so I’m not blind to them.
DHW, 60 gallon, is indirect fired off the boiler. RFH with outdoor reset on the first floor and 2 baths on the second. Balance of second floor is FHW baseboard. Design temp I’ve been told is zero degrees.
House is in the Moosehead Lake region of Maine. No difficult exposures, temps were mostly mild this year like most places have been.
From 11-30-06 to 3-12-07 we have burned 874 gals of LP. House is set at 60 unless we are there when we turn it up to 70. We have stayed in the house for maybe 20-25 days in that time frame.
I have priced replacing the gas burner with an oil unit. My cost is just over 700 bucks, no labor included. I have 2 oil tanks coming out of a house we will be tearing down so they are free. Running the oil line will be a PITA but I can cut it into the floor and patch myself. Coring the foundation for the oil fills and tack vent is not a problem.
Am I second guessing myself here? I was planning on calling the heating co to get their ideas also.
Replies
Close to 10 gal propane a day and only there 1/3 of the time?
Have you done a detailed check for a propane leak?
Other than that get the the first floor joists insulated, big $$ going out there.
insulate first, and generally when we do radiant off of a system 2000, we use an IDFWH "shell and tank" design, and inject out of the shell for the radiant.. that way, the DHW tank acts as a buffer. Seems to work very well, though you better have a tempering valve on the DHW tank.
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Rob,
The RFH is running off a TACO Radiant Mixing Block. I'm sure you know of the one I'm referring to. Are you saying that I'm still better off using a storage tank to have the volume to work off of instead of relying on the storage of just the boiler? I'm not arguing the point as it makes perfect sense to me and fully agree that it would prevent the constant short cycle of the boiler. Do you think that this is the real issue along with lack of insulation in the floor?
It's a simple job given my current set up. 90% of the work is in place. If so, what size tank are you thinking about?
EDIT: I would install a seperate tank for the storage if required. I shut off my DHW when I'm not there.
Your input counts.
Thanks
Rob W
Edited 3/19/2007 5:10 pm ET by RobWes
Hi Rob,It's always hard to say, since we always do it this way I am not sure how big of a deal it really is. But my partner, who knows that end of things better than I, agrees that bufferring is pretty important with the system 2000 on radiant systems.The flip side of this Rob is I get calls all the time from people who "just have the floor left to insulate" but in reality, there are lots of little things not buttoned up yet that cause leakage, etc. Are you sure you are not one of these?Regardless, I would not even start paying attention to fuel usage until you are done insulating. That could double your heat load right there under the right conditions. And you may find the short cycling less of an issue then too. So start there, and "get funky" later if you need to. But don't start with the funk! It's just too funky. Dig? ;)Maybe I shouldn't post when Stevie Wonder is playing.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Thanks again for your time.
I assure you that the floor is the only item left. Sorry I don't know how to post pix to show. I will plan on insulation ASAP prior to going any deeper into this. Too late for this season. I've just been too busy w/ other things in my life. Thus, the reason the place has no use.
I'll try and order stock for delivery this week and get started.
I just love FG! :-( I should have had the subs do it.
Rob
Couple of random thoughts here...FG is not a great insulation, but it is true that this winter was mostly mild. One house I check used hardly any fuel until Feb when winter finally hit. Then we had six weeks of cold and NW wind from hell or Canada. That wind can really reduce the effectiveness of FG in the cold.I am in penobscot bay, BTW.I am suprised that you opted for the pgas. Propane here in Maine is very expensive per BTU compared to oil.On re-using oil tanks - a lot of installers will not do that because of the greater possibility of leaks from rust through, esp if over ten years old. They have to balance liability vs. cost savintgs. A tank isn't that much.Finish insulating and see if you can get a blower door test to find spots of infiltration first before rebuilding the heating system.
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Thanks for your input. The tanks are quite new. We needed to remove a 4000 gal UST per town bylaws so we installed these HD 330's 5 years ago. I would just hate to toss out perfectly good tanks that have been indoors and never seen a drop of rain. The house is in the way for a 35 lot subdivision we are planning on 150 acres here in Carlisle.
The original plan for the house was spray foam. When the numbers started coming in we were knocked over. As such we bagged it. I recall something like 3X the cost. The basement is a 10' pour and the rim is well insulated with rigid due to a major design change. (long story)
I'll plan on doing the floor insulation asap. I won't get to know my results till next year. The original plan for the house was 2 heating fuels. Using 20/20 looking back I should have kept with that plan. The ease of LP was the clincher as we were cooking and running the genset off it no matter what. I never really focused on BTU per gallon of fuel while planning. That's what has me second guessing myself now.
Someday I'll see the coast of Maine. To date it's only been Wells Harbor as I fish out of there with friends.
Five year old tanks are probably fine then.Keep in mind that they can rust from inside too. water in fuel will settle to the bottom and rust there. Check that as you empty and move them.
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Rob before you change to an oil fired boiler you need to address the short cycle issue or else leave your oil fired boiler run on the high limit(not very efficent). My previous experience with this type of setup resulted in a once a year mess when it came time to clean the boiler. A propane fired boiler is much more to tolerant to cooler boiler temps. Roger
My plan is to insulate the floor first and see what happens. Secondly I will look much further into having some more "mass" to work the RFH off of. This makes too much sense to me for it not to help. A tank in a tank set up is simple work and most of the piping is in place.
If for nothing else I know that I can change over my System 2000 to oil w/o a whole lot of work. Makes me glad I at least bought the unit. Even more happy is that I didn't do the power vent option, I'm venting into the chimney using a draft inducer.