Geothermal Spa

Alan (California Radiant) Forbes

I spent the last week in the California mountains consulting with the people in charge of operating and maintaining hot springs at a retreat. It's been there hundreds, maybe thousands of years before the native indians found it and white settlers moved in and supplies the facility with DHW, radiant floors and ceilings in the common areas, radiators in the guest rooms, spa pools, steam rooms and swimming pool heat.

Many of their distribution systems are old, out of date or need to be modernized and they are looking for recommendations. I have no experience with geothermal, but know a bit about moving water and distributing heat. So, rather than trying to reinvent the wheel, I'm asking here to try and find a person or publication that can steer me to a design that is already in use and that works.

There are two hot water springs, rich in minerals. One of the springs has two Grundfos 26-150 pumps in series supplying the room radiators, DHW for the kitchen, radiant floors and ceilings and heated water for the pool. The other spring fills a 1,200 gallon tank that supplies the steam rooms, spas, radiant floors in a couple of buildings and DHW for the showers and lavs. Various heat exchangers exist.

The Grundfos pumps are open to the weather and covered with plastic bags in the rainy season, some of the hot water is wasted back into the steam next to the hot springs, pipes are breaking, heat exchangers clogging up..........

leonz

Hello Alan,

You should have them invest in the Certainteed Certa-lok Yelomine Pipe which is heat, acid and buildup resistant and you can use traditional Victualic pipe, valves, gauges, fittings, pipe clamps and gaskets to allow for easy pipe joining and maintenance using the Victaulic hand groover for making the pipe joint grooves and cleaning the pipes as needed.

The Certainteed folks have a Distibution center for pipe and fittings in Reno, Nevada and I have the number for the manufacturing plant in Lodi, California 1-209-365-7500 and I am sure they will get you in contact with their distribution center in Reno.

HomerJSmith

I might make a suggestion on this situation. I can see the mineralization on the pipes. Hot spring usually have high mineralization. That means that the piping has deposits inside all the piping and heat exchangers. Even plastic piping can calcify. It only takes several millimeters of calcification to reduce heat transfer.

The cast iron pumps can maybe cleaned and used again if not destroyed by oxygenated water.

I think that I would separate the mineral hot springs water from the heating water with some kind of heat exchanger in the pool. A coil of Pex A in that pool would likely serve as a heat exchanger. What do you think?

The existing piping may need a though de-calcification and cleaning.

FStephenMasek

Where? It sounds like a place I'd enjoy visiting.

HomerJSmith

Probably in Napa, have some wine and cheese with a good soaking?

Jamie Hall

Two things I'm really not at all happy with. First, two pumps in series suggests that someone didn't bother to select the correct single pump -- or that over time the mineralization in the pipes built up enough to restrict the flow (no surprise) and someone kludged an extra pump on there to "fix" the problem.

Second, while you really need the mineral water in spas and such places -- that's what the customers are paying for -- you don't need it nor want it anywhere else. Where heat is needed -- domestic hot water or a fresh water pool, for instance -- that should be fed by heat exchangers with as short a mineral water circuit as possible.

hot_rod

Are the Grundfos pumping from an open pit? They need some npsh to have a happy life.
How hot is the water?

I think Mark Eatherton worked on some of the Colorado hot springs, I recall something about ceramic heat exchangers due to very aggressive water.

Alan (California Radiant) Forbes

@HomerJSmith Not Napa (further south), but Calistoga just north of Napa has hot springs and that is probably a good place for me to visit to see how they manage their hot springs water.

@Jamie Hall Often two smaller pumps (in series or parallel) are cheaper than one large pump. But to tell you the truth, I don't know the answer. So many people - qualified or not - have had their hands on this system.

@hot_rod The first picture is the pit where the hot spring water is collected; 135°F.

From Wikipedia: "Analyses of two of the thermal waters showed them to be noticeably sulphuretted, and only moderately mineralized."

Mad Dog_2

Very interesting job.  Please keep us posted.  They're not hot, But Saratoga Springs New York is Famous for its mineral springs bubbling up all around town, in Congress Park and even at the Racecourse.  Heavy sulfur smell and taste.  The marble fountains look to be Early 1800s, but I will look closer next time at the effects on the mineral-rich water.  Mad Dog

Larry Weingarten

Hi, I'd like to second this, that @Jamie Hall said: "Second, while you really need the mineral water in spas and such places -- that's what the customers are paying for -- you don't need it nor want it anywhere else. Where heat is needed -- domestic hot water or a fresh water pool, for instance -- that should be fed by heat exchangers with as short a mineral water circuit as possible."

That sounds like a nice guiding principle to have when figuring out what you want to do there.

Yours, Larry

leonz

110 volt pump jacks for this hot water are a perfect solution for this as the ball check bronze cylinders would work trouble free for decades just as they do in deep crude oil pumping.

hot_rod

Id ask for a recent water analysis to see exactly what you are dealing with for quality