Using Hot Spring Water for Radiant

Alan (California Radiant) Forbes

I’m working at a retreat; California Central Coast where they have an ancient hot spring, using the water to heat one of their buildings with a 12 year old radiant system with PEX tubing. 

They have a shell and tube HX which is not working because the hot spring water temperature is too low - 130F - and are considering a flat plate HX. 

They have another building that uses the hot spring water directly to heat the floors - no HX and it’s been working fine for years and I’ve suggested they do the same for this building, i.e. remove the HX and pump directly to the floor. 

From what I’ve read so far about the water quality there, the mineral content is low, but there are sulfur compounds. 

Noteworthy is that there are a few Grundfos 26-99 pumps, one of which I took apart the last time I was there. The volute was pristine, no mineral buildup, rust or deterioration. 

Any thoughts on using the spring water directly?  I’ve asked for a chemical analysis. 

Mad Dog_2

So you pull the hot spring water out, through the pex and then it returns back to the source? Any pictures or diagrams?  Sounds very cool .    Mad Dog 🐕 

Paul Pollets

I've done this with a local hot spring. Used a marine grade FPHX and a stainless LV pump. With 130 degree water, you may be able to use the flow directly. Some thermal sources have enough flow to work without a pump.

Alan (California Radiant) Forbes

Mad Dog_2 said:

So you pull the hot spring water out, through the pex and then it returns back to the source? Any pictures or diagrams?  Sounds very cool .    Mad Dog 🐕 

Exactly. There's a 500 gallon tank about 150 yards away that serves multiple uses. Large mineral baths and steam rooms. Immersed in the tank is a HX for DHW for showers.

Mad Dog_2

Awesome....The closest I've seen to this was a Consult I did 20 years ago on the Mountain overlooking The Mighty Hudson River Northside of the Tappan Zee Bridge.  Built in to the side of the mountain in early  1800s, it had a stream running through the basement and a Huge (For the property) old block wall fish tank.  It was about 8 feet wide, 10 feet deep and 15 feet long.  The cold spring water flowed right through it.  It was built for your very own Fulton Street Fish Market 🐟.   The guy was a Professional, well known Bluegrass musician and he had just picked the house up.  I Gave him the NYS Fish Hatchery info  and told him he could stock it with live trout and eat em.  He was very excited.  Hope he did....Mad Dog 🐕 

Paul Pollets

Couldn't raise trout in 170 degree water, which is what the outflow is at the Goldmeyer hot spring. The property was owned by a prospector ( Mr. Goldmeyer) who was looking for gold, but found very hot water. The native Americans had known about the hot spring for many years. It's the last old growth forest remaining in the Cascades and some of the firs have a 15ft. diameter. A grant from Paul Allen preserved the land. It's a 4.5 mile hike to the site and well worth it. www.goldmeyer.org

Mad Dog_2

Cool story....There is a Famous Thoroughbred Racehorse named Mr Prospector....maybe named for him? Mad Dog 🐕 

WMno57

Goldmeyer Hot Springs looks like an interesting place. I checked out the website. However, there are probably over one million acres of old growth forest in the Cascades. Several National Parks and Wilderness areas.

Mad Dog_2

Have Grizzlies returned up there.. heard there is only Black Bears Cougars and Deer 🦌 up that way.  Mad Dog 🐕 

Larry Weingarten

Hi @Alan (California Radiant) Forbes , Sounds like you are on the right track. I’d want to see the water report, just in case something strange were there, but it sounds good. Glad to help if you want 😉
Yours, Larry

Paul Pollets

WMno57-the old growth that remains is in the national forests and national parks where it can't be harvested.

LMacNevin

This sounds like an easy job for PEX tubing; I don't see any issues from that perspective. Talk about a sustainable heating system!

Alan (California Radiant) Forbes

Some photos showing: the dirt road that takes you down to the hot springs. With our very wet spring, my truck had a hard time navigating the deteriorated road. It took 2 hours to travel 14 miles.

The shell and tube heat exchanger to heat the floors of one of the buildings. I have since found out that they chose this type of HX because they were afraid that any sediment or debris from the hot springs would clog a flat plate HX. This type of HX is commonly used for heating swimming pools with systems that have a high ΔT and is not appropriate for what it's used for here with 130°F spring water. The system doesn't perform.

You can see the 500 gallon tank with multiple inlets and outlets. Inside, there's a HX for the DHW in the bath house.

The last picture shows the piping and setpoint control for the hot tubs that keeps the water temperature at a perfect 108°F.

hot_rod

Sure looks like a lot of scale from the water? it must have some high TDS or hardness? most ground water does.

A properly sized shell and tube would be best, or better yet a large smooth coil indirect.

Heatflo can build a high performance dual coil tank, 100' of coil! that would give you exchange close to a plate type HX. An indirect is basically a supersized shell and tube HX.

If you called them with the HX spec you are looking to get, maybe they build a custom tank.

bio_guy

This is what we used to call "geothermal" before that term was misappropriated for "ground source". So what are we calling this type of heat now?

GGross

bio_guy said:

This is what we used to call "geothermal" before that term was misappropriated for "ground source". So what are we calling this type of heat now?

It is still called geothermal. Ground source heat pumps are also correctly called geothermal because they draw energy from within the earth