Solution for heat loss from inground pipes?

[Heffspool]

I'm preparing to add heat to my pool by adding a hotspot energy heat exchanger.

The heat exchanger will be located 200' away from the pool. I am planning on installing 3" line to the pool but looking at the cost of insulated pipe is extremely expensive.

200' of 3" pipe holds about 73 gallons of water. Assuming about a 60gpm flow rate that means the water in the heated pipe takes over a minute to reach the pool.

Now let's assume the average dirt temp of my ground is 55°. I'm really curious how much heat I'll lose.

Since underground rated insulated pipe seemed too expensive, I was thinking about putting the 3" pipe inside of a 5" pipe then at least the hot water line isn't touching wet cool dirt.

What do you guys think?

 

[tim5055]

I think you will have so little loss that you probably don't need to worry about it.

Now, keep us posted on how it works out. I have looked at those but can't get over the cost of the unit and installation. Plus, the time I really need it is in the spring and we really don't run our A/C the to capture the heat.

 

[zea3]

You are far more likely to lose heat from leaving the pool uncovered than having the pipes run under ground. Invest in a good solar cover and leave it on when the pool is not in use. That will help your pool retain heat longer.

 

[Heffspool]

Great news, thanks!

I'll let you know how it works, but in my case I know it's going to be awesome, and way long overdue, but I just found out about these heat exchangers.

My property is a split commercial and residential. I lease the commercial warehouse and they run freezers and refrigerators 24/7/365 about 20 tons worth. So I'm going to be able to heat my pool all year round with the heat byproduct from the warehouse.


For anyone not in my particular situation, the roi is a little harder to calculate. But for me, minus pumping costs it's free heat all year. Also install costs are going to be relatively cheap because I don't need any of sunspots refrigerant valves or controls.

 

[tim5055]

Well, it sounds like instead of a pool you will have a huge hot tub

With all that free heat I would not worry about the "loss"

 

[jblizzle]

Here is an article that has some info about heat loss.
http://geoheat.oit.edu/bulletin/bull22-3/art2.pdf

If I extrapolate the Figure 1 down to 80 degrees and assume worst case soil conditions. The loss would be about 100 BTU/hr-ft. Multiply by 200' = 20,000 BTU/hr ... divided by 500 * GPM {not exactly clear on the 500} gives a temperature drop of 0.67 degrees F

But, that is assuming steady state, meaning the ground around the pipe has reached equilibrium, like for supply hot water. When the heater is not run all the time, there will be higher losses to soil initially.

 

[Heffspool]

Well, it sounds like instead of a pool you will have a huge hot tub

With all that free heat I would not worry about the "loss"

When I first started talking to sunspot they recommended I do 15 tons worth of heat exchangers and to add a waterfall to dissipate some of the heat.

I'm thinking I'm going to go with 10 tons or 5, still not sure. But I certainly could turn it into a hot tub I bet. chlorine costs for a 20k gal hot tub might be a little offensive though.

I would like 81° in the cold of winter, not sure how to calculate my heat needs.