FAQ: Cheaply Keeping a Pool Hot -- 90F,95F,100F -- How we ran till Jan 11th in Canada

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Hi there...good to see you pop back in!
2700 is right around where I run the heater and I agree that it seems to work just as well - I now have a variable speed pump too ;)

I’ll have to check into foam covers...haven’t seen anything like that in these parts! Is it easy to roll?

I just got the dome back up into operational mode yesterday and am looking forward to a super warm physio session this am before my new Portuguese Water Dog wakes up ;)

He’s jealous if I go into the pool without him but he’s a pita when I’m trying to exercise because he’s a bit of a Velcro dog.

Btw, re monitoring — ambient weather now has a 7 channel unit that you can read your sensors online on your phone! Bonus is that it logs the data so this year I might be able to graph my setup.

Cheers to “hot tub mode” and a smooth season for you! Gotta run before the pup is up!
 
Yes..
It's called Blue Shield Poly which is located near Barrie, Ontario, Canada.
Cost me about 4x to 5x as much as the bubblewrap type (that fell apart in only 2 years). It has a 6 year warranty.
They sent me a free sample 1.5 years ago, which I kept until my bubblewrap cover distintegrated.

I think it will pay for itself in both longevity and heat-lock-in savings. Especially with snowstorms and icy rainstorms. Wet bubblewrap with cold standing water on top, rapidly cooled down the pool after a icy rainstorm even when covered. But the bubblewrap doesn't even notice, ice-cold standing water on top doesn't as noticeably cool down the water below -- during a icy storm while the covered pool is hot. Sitting water on top of foam cover doesn't even steam (which generates the unwanted evaporative cooling effect)

Rolls up similarly (existing roll originally used for bubblewrap type cover) and weighs roughly similar, since it's 3 millimeter thick. There's also a commercial-pool variant too. Basically plasticfoam with two tough plastic laminates (on top and bottom sides). I can't rip it, as hard as I might -- much more rip resistant than the bubblewrap type.

As for RPM, I now recommend 2000 RPM during peak TOU rates. Basically weekday expensive time-of-use rates can make the electricity cost feel as expensive as the natgas cost. If you live in a place of expensive peak-rate electricity (places like California,USA / Germany / Ontario,Canada) during a time when natgas is relatively cheap.

So for a given temperature increase to water -- you may be using a few percent more natgas (e.g. few-percent decrease in efficiency or so, like 85%-down-to-82% efficiency heating due to slower water flow) -- yet you're saving roughly two-thirds to three-quarters electirity (~75% decrease in pool-pump electric use). So the electric savings massively outweighs the ultra-slight natgas increase that was not able to be noticed at all. So if you're running the heater+pump through peak electricity rates, I definitely now recommend the lowest pool pump RPM that your specific heater still works very well at. I'm still able to inject the same +25 to +30C raise to water temperature in just 24 hours of continuous heating at lower RPM (at only 250 watts electricity)
 
Swampwoman said:
Btw, re monitoring — ambient weather now has a 7 channel unit that you can read your sensors online on your phone! Bonus is that it logs the data so this year I might be able to graph my setup.
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Nice! I need to obtain sensor monitoring.

[googled that thing] Ambient Weather model # WS-8482-X3 correct? Only ~$85 including a few wireless temperature sensors!?!
(And I can add several more later - soil temp sensor, water temp sensor, air temp sensor)

That's really cheap for 7-channel WiFi temperature monitoring and works with IFTTT automation .... I might be able to program some cheap automation to the pump/heater so that the pump is automatically shut off when target temperature is reached. The heater and pool pump both have GPIO-style triggers, so I just need a small amount of triggers.

I'd try for easy-peasy IFTTT style. But worse comes to worse, I can at least use my programmer skill to add a Raspberry PI / Arduino to help out with cheap automation.... my pump/heater already has relay-wire triggers that would work perfectly fine with GPIO pins of an Arduino/Raspberry PI.

(As written in earlier posts -- this is to prevent inefficient automatic heater cycling. Unattended, the heater automatically shuts on/off/on/off but pump continues running nonstop. But that is an efficiency problem in the winter because of the cold-ground pipe-cooling effect of unnecessarily running the pool pump without the heater -- resulting in more wasted natgas when the heater cycles back on. Because the pool re-cools down faster from that cold-ground pipe-cooling effect of running pump without heater in winter). Scheduled run + calculated temperature delta needed + calculated number of hours based on current water temp and air temp + auto shutoff = less wasted hours of heating & pumping.

I may actually attempt this automation this winter. Let's see...
 
Doing my research now for a possible DIY pool vs Contractors, for a number of reasons. I love water, and love it year round. However, Chicago, allows for a limited "normal" pool season. Spent a lot of time looking to extend the season in my design, and have to say this was the most useful post with actual data supporting some of your techniques that I have read. Not sure if you are still on the blog, but congrats on a very nice job and thanks for the info.
 
mdrejhon said:
New Foam Pool Cover

Been a while, but I have a new upgrade: A foam pool cover.

Basically, 3 millimeter thick laminated foam pool cover.

Cost me 6x the cost of a common bubblewrap pool cover but has a 6 year warranty and hopefully pays off in lower gas costs after just two seasons or so. Initial results are promising.

With raises in gas rates, so optimizing to lower costs even further is important as this is a "luxury" we want to keep doing sometimes.
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Hi There!

I was wondering how you were making out with the foam pool cover. Any signs of wear and tear? I am interested in the same product (Blue Shield) and have asked for a sample to be sent. Our pool is in the Cayman Islands, but even so, it's pretty nippy in the winter time to swim, so I'm looking for a solar blanket to keep the heat in and that will withstand harsh UV rays. Those bubble ones, they don't seem to last as long.

Thanks for your input!
 
Northern Lights said:
Hi There!

I was wondering how you were making out with the foam pool cover. Any signs of wear and tear? I am interested in the same product (Blue Shield) and have asked for a sample to be sent. Our pool is in the Cayman Islands, but even so, it's pretty nippy in the winter time to swim, so I'm looking for a solar blanket to keep the heat in and that will withstand harsh UV rays. Those bubble ones, they don't seem to last as long.

Thanks for your input!
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Only seeing this now.

It is 2021. TThe plastic-sheeted foam pool cover is holding up well. I’d wager 3x longer lasting than solar pool cover. It’s on its third year and looks like it will last another 6-7 years before I need to replace it.

It is WAY more puncture resistant than the old solar cover because plastic sheeting on both sides of the foam, so double the plastic sheeta. Imagine the foam cover as two thin solar cover (without bubbles) AND just opaque “foam plastic” in between the two. so the falling tree branches have never punctured it.

Stains from leaves (since I am the proverbal pool-in-a-forest) are easily de-stained by pouring a jug of pool chlorine on top, scrubbing it, and letting dirty water splash into the skimmer. Convenient, as it is a color that makes mopping easier than a solar cover.
 
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splashpad said:
@mdrejhon How did the 2018/19 winter go?
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Very well! Still using the pool 12 months a year, though some months only had 1 sequence of hottubed evenings (3 day weekends) instead of 2. Gas bills are rising but still only $100-200 extra for the pool’s share.

Thanks to combo or foam blanket cover and judicious weekends (4 day contiguous is more efficient than two separate 2 day weekends 2 weeks apart).

….

Now that the thermal blanket is being used, we are mathing out economics of electric vs natgas. Natgas is cheaper, but the price difference is now smaller.

We may add winter-resistant solar water heating on the rooftop, and use natgas to make up the difference. Or electric combined wirh photovoltaic electric.

Solar water is more efficient in summer, while solar electric is more efficient in winter because of heat losses, so photovoltaics starts to make sorta more sense, since I need PV for other things anyway, so both (hybrid) it is, as sometimes solar water is more efficient, and other times solar photovoltaic is more effivient (at least with 22%-efficiency panels out now. And only some days are sunny.

But heating 70F to 95F is much easier than heating 50F to 95F, so if solar systems can keep the water at 70F, it’s a cheaper natgas/main-electric boost.

If natgas prices keep gping up, there is a day coming where electric will be cheaper than natgas if I have my future hybrid water solar+photovoltaic solar system (running concurrently). And a small bit of nighttime electric (from the grid or powerwall) to maintain temp in weekend evening after a few days of hybrid solar heating to intermediate temperatures that is only a few dollars per evening to boost for days we want full hottub temps.

The thermal blanket seems efficient enough to quit natgas! Eco friendly hottubing, I guess!?
 
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