Another cold night ahead...

J.C.A._3

I've been dealing with a few today that would be the "end all...Be all", but with a twist.

The power(can you say National Greed?) went down at 6:30 last night, and came on at 4:30 this afternoon, in a part of town. BUT, it was random and erratic at best...One person had power, and the neighbor didn't...oneside of the street worked, and the other didn't...?

I pumped a radiant floor full of straight anti-freeze at 7:30 this A.M. and managed to catch it JUST before the freeze had set.(Poor outside insulation)When I started the handpump,I encountered some resistance but it only lasted 3 strokes and the flow was established.

Nothing like catching a slab radiant freeze in the "Nick of Time". I must say that it was the Lady of the home that made the call to Scott.(GOD bless her) For some strange reason...SHE knew what the effect of the radiant slab freezing would entail, and made the call.

Her husband, on the other hand...was just thrilled that he got a hot shower....but never thought of hammering up the kitchen slab for a re-pipe if it froze.

Design Temps aside....I think alot of folks learned a lot about their homes today...and it will continue into tomorrow morning for sure. Trust me... Chris

Constantin

Looks like design day conditions to me...

... all ye homeowners in the NE thirsting for a quick and dirty heat loss calculation, getting up tomorrow morning in the AM (before the sun comes up) and clocking the boiler/furnace for an hour may just do the trick. The wind and temperature's we're experiencing seem to mimic design day conditions quite nicely.

On most oil-burner equipment, simply note how much the burner runs over the course of an hour, then use the nozzle size + pump pressure + a chart from the nozzle manufacturer to determine how much oil was used in the process. You can get this data during the annual check-up from the technician.

Once you know the thermal performance of the boiler (also found during the check-up), you can factor the two and multiply the result with 140,000 to determine approximately how many BTU's your home needed to stay at temperature.

For gas users, there's always the meter to look at. Simply note how many therms of CCF of gas your heating appliance went through over the course of an hour. With the thermal performance data you can get from the technician during your annual checkups, you'll also have a good idea where the heat loss is. A CCF or therm of natural gas contains (at sea-level, under normal conditions) about 100,000 BTUs.

Naturally, this is not an exact heat loss calculation and many factors could influence the results. Furthermore, it doesn't give you an insight into where and why you're losing the heat. But it does provide an interesting data point to consider.

May everyone make it through this cold spell safely, I already met one very unhappy homeowner with a K.O.'d heating plant today. So stay warm out there, and if you plan on venturing beyond suburbia, bring the kind of stuff that will keep you alive until the help arrives.

Constantin

I know that feeling...

Back in school, student housing was either served by the transformers at school or the local grid. For some reason, squirrels really enjoyed electrocuting themselves on the school transformers with spectacular results... the whole school grid would go down, the most memorable occasion being on a night during final exams. (Imagine roving bands of students heading for any house that still had power.)

On my way to work yesterday, I was struck by the absence of smoke coming out of chimney's everywhere. It was about 10°F, the sun hadn't been up for more than a peek at that point, yet 2/3 of the houses I passed did not have little clouds coming out of their chimneys. Given that

• there are very few remaining electric-heat customers around
  
• correctly-sized heating plants should have been running close to 100% in those conditions.
  
• fewer than 1/3 of the houses featured chimney/flue smoke

the (admittedly cursory) evidence suggests that there is a lot of savings potential out there due to oversized heating plants.

Congrats on that save of yours and may more customers come to appreciate your skills and knowledge. Higher fuel prices may drive consumers to become better educated, change behaviors that you and others had to suffer under (i.e. run the boiler until it breaks, maintenance?)

zeke

You have to multiply your results by the duty cycle to be more accurate, the duty cycle being
Ton/(Ton +Toff)

Constantin

Thanks for pointing that out, Zeke.

Evidently, my recommendation to note the "on time" during that hour of testing was not clear enough. So yes, note how many minutes the boiler is firing during an hour, then multiply as needed:

BTU's consumed x boiler thermal efficiency = heat loss

where

BTU's consumed = the fraction of "on time" per hour x input rating of boiler

the input rating on boilers depends on the burner used. Many boilers only have one input rating, though some residential units are step-fired or modulating. For gas units, I'd look at the gas meter to determine how much fuel was used over the hour. A call to the utility to determine the caloric value of gas is also recommended since high-altitude gas supplies tend to have less heating value per ccf/therm than low-altitude supplies.

For oil-firing units, the input rating depends on the boiler, the orifice, and the pump pressure. Hence my recommendation to have a technician check out the unit, determine the pump pressure, etc. After all that, you can determine how much fuel was used over the hour, which combined with the thermal efficiency of the plant gives another yard post in heat loss land.

The neat thing about calculating the heat loss this way on a design-day is that you minimize the standby, start-up, and shut-down losses. They still interfere, but their effects are minimized.

Mitch_4

do it all the time

I am exceeding design temps (FHA system) replaced the old 120K input with a 60K high efficiency, which by heat loss was a borderline choice at best.

At temps exceeding design it runs 10 mins on, 10 off, totalling 1/2 hr run time or 30K input or a heatloss of 28K/hr this was at -33°C with a heavy wind in a 2000sq ft 30 year old 4 level sidesplit original everything.

Think there is a bit of padding in the Heat loss programs?

You betcha...

still my bill is down about 46% so I aint complaining.

I still try to get to the site and clock cycle times before a replacement if I can.

Mitch