Insulate Well Tank?

[josephny]

I'm having a hard time figuring this out.

I have a 12' x 18' well house with a 5 pitch roof.

The structure has a single 2' x 3' double pane window.

Roof rafters have 6" of open cell foam.

Walls have 3.5" of closed cell.

6" slab on grade has 2" of closed cell on top of it.

Well head is inside structure, coming up through concrete and feeds a 100 gallon galvanized (non-bladder) pressure tank (through a few feet of pipe with pressure switch).

I have a 500 watt, 220v heater for the structure, connected to an Ecobee thermostat (so I can monitor and record the inside and outside temp, as well as control the heater).

Now that it's cold here in NY (this is the first season with this setup), I'm surprised at how much energy it is taking to maintain 45* F inside this structure.

I've attached the data -- outside temp just above 30*F, setpoint at 45, looks like about 50% on/off.

I'm trying to figure out where the heat loss is and the only thing I can come up with (other than simply insufficient insulation, which would be surprising), is the pressure tank and piping.

I think the water temp is between 40 and 45.

Could the tank be the culprit -- sapping the heat?

If so, should I insulate the tank? Wouldn't that be weird considering the heat source (other than the well water's temperature) would be coming from outside the insulated tank?

Thank you,

Joe

 

[LouNY]

You don't say how high the walls are. But that is 216 sq. ft. You are only using a 500 watt or 0.5 kw heater or 1700 btu/hr.
If your electricity is $0.16 per KW, your cost is roughly $0.08 per hour of operating time.
Also that 2x3 window is a large heat loss, cut a piece of foam board and seal that window tightly if you were to check the glass
temperature you would be surprised how cold it will be.

 

[josephny]

You don't say how high the walls are. But that is 216 sq. ft. You are only using a 500 watt or 0.5 kw heater or 1700 btu/hr.
If your electricity is $0.16 per KW, your cost is roughly $0.08 per hour of operating time.
Also that 2x3 window is a large heat loss, cut a piece of foam board and seal that window tightly if you were to check the glass
temperature you would be surprised how cold it will be.

Side walls are 8' tall (peak is about 10.5').

That's great advice about the window -- I'll do that.

Yea, 500 watts (1700 BTU/hr) isn't much, but I figured that so many people talk about using a single 100 watt light bulb, that I'd be okay.

Thanks!

 

[josephny]

Found this nice calculator at:

Heat transfer/loss formula and how to calculate it

Shows that my 2x3 window loses about 50 BTU/HR

Think that's right?

 

[LouNY]

We keep stock waters thawed with 60 - 70 watt light bulbs, but the area being heated is only 1 to 1 1/2 ft by 2 to 4 ft and 2 ft high so just a few cubic feet 4 to 8 with no
drafts or air infiltration. A lot of well houses are only 6 x 6 or so with flat or single slope roofs and many of those are 80% below grade. If your tank is in a corner and your heater is also,
where is your interior temperature sensor? There can be considerable temperature stratification in a room that size, even at 45 degrees I would not be surprised to see a 5 to 8 degree difference in temp in that room depending on location. Good luck keeping your water flowing this winter.

That looks like a good calculator, handy to have

 

[square1]

Why 45 degrees? There are considerable amounts of time the temp is above freezing but lower than 45 degrees. In any case, the water coming up from the well is propably > 45 degrees so it is helping to heat the well house. Short excursions below below freezing isn't going to freeze a 100 gallon tank. If the lines are insulated and traced they aren't going to freeze either. I'd lower that T-stat 5~8 degrees.

 

[josephny]

We keep stock waters thawed with 60 - 70 watt light bulbs, but the area being heated is only 1 to 1 1/2 ft by 2 to 4 ft and 2 ft high so just a few cubic feet 4 to 8 with no
drafts or air infiltration. A lot of well houses are only 6 x 6 or so with flat or single slope roofs and many of those are 80% below grade. If your tank is in a corner and your heater is also,
where is your interior temperature sensor? There can be considerable temperature stratification in a room that size, even at 45 degrees I would not be surprised to see a 5 to 8 degree difference in temp in that room depending on location. Good luck keeping your water flowing this winter.

That looks like a good calculator, handy to have

Yeah, it is a big well house. Originally built in the 1930's, so I figured might as well keep the same size.

Heater is at ground level near midpoint of 1 of the 18' walls.

Tank is in opposite/diagonal corner.

Tstat is about 8' down the same wall as the heater, towards the same 12' wall that the tank is on; and about 5' off the floor.

5-8* is more than I would have guessed (I'm absolutely not a pro, so I'm not implying any validity to my guess).

Think I should change anything?

Thanks!

 

[LouNY]

At this time you are not having any problem keeping it at temperature.
If you are concerned about the amount of heat being used and the possibility of not being
able to keep above freezing you could get 3-4 sheets of foam board and box in the corner
were the water tank and piping is, move the heater and t-stat into that corner and reduce
the area you are keeping at temperature to just a few cubic feet.
If you need to keep the entire room above freezing because of other items stored in it,
you are on the right track and until your heater is on 100% and not maintaining you are
good, you could always add a heat lamp in the corner with the tank and piping.

 

[oosik]

That 1930's well house is gigantic compared to most built today. Most I inspect now-a-days are 4x6 up to 6x8. And Yes, they are being heated by a couple 100 watt light bulbs.

Example - my electricity costs 6.5 cents per Kw here. I have an completely insulated, sheathed Tough Shed - 10' x16' where I store my motorcycle. I have a small 1200 watt electric heater in the shed. Its set to keep the shed at 48 degrees during the winter. On our coldest month it will add $19.00 to my overall electric bill.

You are heating a lot of dead air. Seal off the window and figure a way to decrease the size of the heated area by hanging a sheet(s) of clear roll plastic. All you really need to heat is the well head, plumbing and pressure tank.

 

[josephny]

Why 45 degrees? There are considerable amounts of time the temp is above freezing but lower than 45 degrees. In any case, the water coming up from the well is propably > 45 degrees so it is helping to heat the well house. Short excursions below below freezing isn't going to freeze a 100 gallon tank. If the lines are insulated and traced they aren't going to freeze either. I'd lower that T-stat 5~8 degrees.

The lines are not insulated or traced. I thought I wouldn't need that if the entire well house is insulated.

If the water is >45*, does that mean that the tank and lines are not a source of heat loss is the temp inside the well house is 45?

Should I lower the tstat to 40, to keep that extra buffer for heat stratification?