Who's Burning Coal Straight Through the Summer for DHW?

I'm running our boiler straight through the summer, and I was wondering how many of us will be doing it this summer. I expect to lose a bit of money in doing this, but it won't be much vs. electric hot water.

If I assume 385 KWH per month for the electric hot water tank, and 15.5 lbs. per day for coal (at $243/ton), on a monthly basis it comes out like this:

30.6 days/month x 15.5 lbs coal per day x $0.1215/lb. = $57.63 per month for DHW from coal

385 KWH/month x $0.132/KWH = $50.82 per month for DHW from electricity

Difference = $6.81 per month, favoring electricity

Over the 5 months from May through September we will lose about $34, but I figure that we have already gained nearly $1,900 by heating with coal this brutal winter vs. electricity, so losing a mere $34 over the summer seems OK by comparison.

I have separate electric meters on my house, one for the regular line and the other for my hot water tank, this shows up on my electric bill seperatley. My hot water electric never cost me over $20.00 per month, mainly around $15.00 to $18.00 dollars per month, and that's with a 80 gallon tank.

Perhaps my estimate of 385 KWH per month is way to high then?

If I guess 75 gallons of hot water used per day, then it comes to:

75 gal. x 8.33 lbs/gal x 70 degrees of rise = 43,733 BTU's per day

43,733 BTU's/day x 30.6 days/month = 1,338,230 BTU's/month

1,338,230 BTU's/Month/3,412 BTU's/KWH = 392 KWH/month (which is pretty close to 385)

What it must come down to is that we are using well less than 75 gallons of hot water per day.

theo wrote:I have separate electric meters on my house, one for the regular line and the other for my hot water tank, this shows up on my electric bill seperatley. My hot water electric never cost me over $20.00 per month, mainly around $15.00 to $18.00 dollars per month, and that's with a 80 gallon tank.

Unless you know how many gallons you use and how many kwh the tank required...$20 per month is meaningless as a comparison for the rest of us.

Edit: I didn't mean to sound harsh...just pointing out that your monthly cost might not be achievable for others. e.g. You could use very little water and pay $0.03 per kwh.

I intend to burn all summer. Might have to burn some oil if I get another bees nest in the chimney.

The Binford will be making hot water all summer just like last year.

Have no idea on how many gallons of hot water we use per day, have electric bill in hand right now. We used 132 KWH for this billing period of 29 days, total bill for the hot water is $15.51 for the month. Now they have different prices marked on the bill for charging, one is 0.061810,price to compare default service,,,,,, then distribution 0.023788.

I just looked at the "Energy Guide" sticker on our 13 year old (bargain basement, not high efficiency) 80 gallon electric hot water tank, and it states that "This model uses 5,162 KWH/year", which comes to 430 KWH per month. That would have been computed for the average family of 2 adults and 2.5 children, and most of the time there are only the wife and I at home, so perhaps we are only using about half of that, or 215 KWH per month for DHW?

That changes things as follows:

215 KWH x $0.132 = $28.38 per month to heat our DHW with the electric tank

That being the case, we are losing about $29.25/month by heating our DHW with coal, or $146 for the summer.

It also calculates to about 41 gallons of DHW being used daily between the two of us.

I really have no idea on how many gallons of hot water we use per day, Also if you burn through the summer is that not making heat throughout the house so it would cost more to run the air cond. to cool the house down?

theo wrote:I really have no idea on how many gallons of hot water we use per day, Also if you burn through the summer is that not making heat throughout the house so it would cost more to run the air cond. to cool the house down?

I'm not sure how much it heats the house, but there would be some heat radiated for sure. Our boiler is in the basement, in a walled off boiler room that sits between the "usable" basement and the garage (as our garage takes up half of the downstairs/basement). The boiler room is walled off to isolate it from the garage, but it is open to the basement.

theo wrote:I really have no idea on how many gallons of hot water we use per day, Also if you burn through the summer is that not making heat throughout the house so it would cost more to run the air cond. to cool the house down?

How many people live in your house? We have a family of four, with two young boys. My basement usually stays 72-75 degrees in the summer. The thick, uninsulated concrete walls keep the temperature pretty mild. Actually, without the coal boiler in service the basement gets cool and damp, with lots of condensation on the cold water piping. I used to run a dehumidifier for most of the summer, but not anymore.

How do you calculate the longevity extension of the boiler by not shutting it down? What is this "AC" you speak of?

Rob R. wrote:... Actually, without the coal boiler in service the basement gets cool and damp, with lots of condensation on the cold water piping. I used to
run a dehumidifier for most of the summer, but not anymore.

Our pipes used to be dripping with condensate during the summer, and now they (along with the floor) stay dry with the boiler running, so we are seeing the same benefit.

mozz wrote:How do you calculate the longevity extension of the boiler by not shutting it down?

...flue pipes and the possibility of developing a leak especially around gaskets.

mozz wrote:How do you calculate the longevity extension of the boiler by not shutting it down? ...

I'm not sure how much life it actually adds, but I know that it costs thousands of dollars to replace one, and sacrificing $146 each summer to keep the boiler from rotting out would buy you 24 years if the replacement cost is $3,500.