Solar design help

Wayco Wayne_2

has an 80 gallon electric water heater with about 100 heating elements. (exageration) I worked on it for free a long time ago since the elements have burnt out now and then. When I was at a meeting last Summer the board was complaining that the electric bill at the pool was high. I remembered the water heater and thought to myself that there could be some relief with a solar thermal assistance. I was thinking drainback. 4 panels and an undersized tank so it could build up heat quicker since there is a lot of use during operating hours and no real benefit for storage. Mayby a reverse indirect like an ergomax or it's equal for the pre heat tank. Maybe I'm getting too fancy and should just install a batch heater on the roof. As long as it can be drained in the off season. Any feedback is welcome. WW

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hot_rod

a pool collector

would probably be the best bang for the bucks. it will outperform flat plate and evac tubes under summertime pool conditions.

Go to the SRCC site and pull down any pool collector and any flat plate and compare the output.

Pool collectors are simple and easy to install, no heat exchanger, just pipe pool water through the pool collectors. Inexpensive to purchase also.

It's about the pool operating temperature, and ambient, which is shown in the upper left of this graph.

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krobe_2

pool showers

While on the subject of pool showers, what type of solar thermal would be economical to install for outside showers? (Summer use only, we're on the Jersey coast) and pass the plumbing code. After time on the beach these showers get plenty of use.

Unknown

Here's something you might want to take a look at. I haven't used it myself but have talked to people who were really enthusiastic about it. Anyone connected with the pool business familiar with it?

http://www.flexiblesolutions.com/index.shtml

Edit: Hi Wayne- It crossed my mind that you might be talking about a shower heater but since economy seemed to be a concern of operating the pool, thought I'd mention the above product.

- Rod

Wayco Wayne_2

I was refering

to the shower water. Sorry for not being clear. WW

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Wayco Wayne_2

A Batch heater comes to mind

Perhaps depending on the situation


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hot_rod

yes, batch

heaters are getting a big push in so cal and other warm areas. Low installed cost and simplicity are a big draw.

I spotted this clever, simple collector at a recent show www.suncache

The Rheem Solarhart is another that has been around for many years. For that summer only use, a batch heater could be a good choice.

hot_rod

for a beach showr

check out this system from Sun Spot Solar. It uses an evac tube built into the stand.

Larry Weingarten

Or maybe...

... a Howard Harris Builders (www.howardharrisbuilders.com) tank hooked up drainback, with a pressurized coil inside supplying the shower? Use collectors appropriate to the showering/pool season.

Yours, Larry

Andrew Hagen_2

Instantaneous SDHW?

To really transfer the heat quickly, I would do a drainback system with an external heat exchanger. No glycol anywhere and use flatplate collectors. You don't need a lot of storage volume, because you will be using the system basically like an instantaneous water heater, which is what I would feed with this system. You will want a little water volume so the system doesn't short cycle, maybe a 40 gal water heater as your drainback tank and a very high ratio of collector area to storage volume, maybe 0.25 gal/sf or less. I am shooting from the hip on these numbers as I have not done this. I agree there is no benefit to storage because it would take a huge volume of storage to cover even 10 minutes of hot water load with the bath house showers. You have the ideal situation for this type of system.

hot_rod

Ergomax as drainback

this is the one in my shop. The tank capacity is the drainback with plain water.
Four 4X8 panels supply the tank. I have a small recirc pump that moves DHW from the Ergo copper coils into the solar Phoenix tank capacity. It runs off the second delta t function of the I solar controller. The Caleffi drainback controller has this dual output built into it.

I haven't tried it as an instantanous, I should. Right now it runs until the Phoenix gets up to 160F, shuts down and drains back, usually by noon this time of the year.

I suspect any indirect with a generous coil of stainless could be used as a pre-heat to the electric tank. Solar in the tank, cold water into the coil which feeds to the electric tank.

Or a dual coil indirect with copper or stainless coils. Feed cold into the bottom connection of the bottom coil. Jumper the two coils together, feed to the electric tank from the upper connection of the upper coil.

Here is an example of a PV powered dual coil piped that way. I'll have it at the RPA show next week. Hope we get some sunshine!

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Andrew Hagen_2

Nice

Could the jacket on the Ergomax be filled with icynene? Have they changed the insulation method that you know of?

Very cool. I love this stuff. The PV guys are missing out.