Finally close to Design-Day Conditions!

jp_2

Is that correct?

how large is the boiler?

Constantin

A good wind and temperatures now down to the teens...

... and the boiler ran about 55% of the time today. As predicted, the VB2-33 is not as good a fit as the VB2-22 (that I wanted) or the VB2-18 (which presumably would have negative margin if the conditions went down to the -15°F we saw for one week in 2003-2004). I guess I should have started pushing back harder, sooner. Oh well.

Not that the VB2-33 is a bad boiler! Ms. Vitola has been keeping the house nice and warm, most zones are running, and it finally feels like winter (how about that).

More importantly, I hope everyone in the midwest and other parts affected by the freezing rain, etc. will have power and heat back soon. May everyone with a genset have the wisdom to only run it outside, to refill it safely, etc.

Homeowners in the Boston area: if you're contemplating replacing your boiler, today will give you good conditions under which to clock the existing boiler and see how much heat your house is actually losing. If there is wind again tonight and temperatures continue to hover around 9°F, conditions will be pretty close to ideal design-day conditions for our local climate.

[Edited to remove descriptor error:] Interestingly, the calculated heat loss for the structure (12BTU/ft²/hr with ~55HDD) matches the actual heat loss quite closely. Or converting to Uni R's scale, 5.21 BTU/ft²/HDD.

Brad White_9

I think Constantin means

5 BTU's per Hour per Square Foot per Degree-Day, not per Square Foot overall. Heck of a house otherwise!

Xc8p2dC_2

Feel your pain

Put in my Ultra in Nov and have been begging for the temps to drop to DD so I can fine tune... Hit 11 degF [dd9 on cape], currently dialed down to 38K btu input max at 150w-t [fintube]and still overshooting Tstat.....C'mmmmon cold

Uni R_2

5BTU/SF?

That's truly an amazing number. Constantin, what's the overall heated area ims Schlo

D107

calcs

so for homeowners who may want to compare: e.g. if my gas use for the month is .166DD per (X) therm (roughly 100Kbtu?)= 16,600 divided by 1800 sq ft = 9btu per degree day? (Note indoor temp of 65, night 60 on this old, badly piped cast iron in-series system). Heat Loss 40K--not sure how to link that. Boiler DOE 165K.

So Constantin keeps day temp at 70; though I've partially insulated (saving 30-35% from last year) and two of my zones are at 60deg for 18 hrs/day weekdays, 9hrs/day weekends, he's got to be expending at least 3x less fuel than me per degree day.

How about a Wall video tour of your house Constantin? Great job.

Constantin

Hi Steve,

Looks like I got the descriptor wrong, I meant 5.21BTU's/ft^2/HDD, not 5BTU's/ft^2/hr like I wrote earlier. Sorry about the confusion!

I still see no reason to switch to a Vitodens given the local market prices for oil and natural gas. Last time I checked, I could get a gallon of B5 low-sulfur oil for about the same money as a therm of natural gas. Go figure!

So, Ms. Vitola will keep on plugging.

[Yet another Edit, ARGH, Maybe I do have BSE!]

Constantin

Temperatures vary little in the house...

... it's about 65-69, depending on what zone you're in. The warmer zones are the ones we spend the most time in. The basement does not have to be as warm.

On the other hand, just the whole house air circulation I set up ensures that the basement stays at 63°F just from the air circulating 1/3 of the time. After making the discovery that it turned my house into a quasi FA house (where other zones were working overtime to make up the heat loss), I turned the basement up to 65°F. Now the first floor zone "fires" less because the basement isn't stealing BTUs anymore.

As for your calculations, they sound plausible, though I would focus on reading the actual meter on the beginning of the evening and in the morning while it is this cold (to eliminate insolation as a factor). Subtract any hot water usage (easily done by comparing it with the summer consumption), and you have some heat loss numbers to consider.

So, if your 9 and my 5 is correct, my house is using about ½ of what your house is using to stay warm. I haven't accounted for hot water usage via the indirect + recirc, so that could drop me somewhat lower.

Uni R_2

Ahhh...

Who is Andrew? I'm a Steve outside of here...

Yes, it's nice getting that extra 40,000 for the same price. Does your figure include DHW production?

Constantin

So far, yes.

I could try to tease those apart, but what I liked about the figures this morning is that until about 6 AM the recirc doesn't come on and the tank "coasts"... More tomorrow, I have a flight to catch!

D107

actually my number was an average from mid dec to mid jan

The colder the weather usually the less efficient--with my old system anyway. Your calc is on a design day; that's why I said my 9 btu to your 5 btu probably is more like 3 to 1. so what is your DD per therm #. On a design day I'm probably looking at .166 to .180DD per therm. You must be .080 or less design day and even less season-wide.

I can't wait for the day when I can fully insulate and put a new system in in a few years with correct non-series piping. Your work and others on the wall shows us the way.

Thanks,

David