Solar & Tankless Combined

ExpressFive

Does any plumbers have experence using solar water heating and a tankless water heater combined? I have a customer who wants to use solar most of the time but wants to have the tankless htr take over when the tempeture drops below a certain degree. Does any one have a soleniod valve brand that could switch from one system to another automatically?

Putty Truck

You have to be in California.

No, it hasn't come up here. Mostly because the people who are spending the money on endless hot water could give a flying fish about solar. That and it rains 366 days out of the year.

Good luck with that.

ExpressFive

You are correct, I'm in So California.

My client has an exsisting solar system and then runs it through the regular gas water heater. With the tankless gas heater it only kicks on when there is suffecent flow. I want to bypass the input line on the tankess for most of the time using just the solar system. Then either at night or sun-less days have water divert to the tankless. I should be able to use some type of aqua stat on an automatic soleniod valve to do this.

Any takers out there in Arizona or New Mexico might have done something like this?

thom

It should work fine to come out of the solar tank and through the tankless heater. If the solar tank water is up to temp the tankless should reduce or eliminate the fuel to the burner so as not to overtemp it.

I use solar panels and a tankless to heat my house. It's been working fine for 23 years.

J87513

Hey dude, I'm a solar guy in CA. It depends if the domestic solar system is passive or active. All that they do is preheat the water for the tank.

passive, right above the tank there is a four way valve set up and the water comes from the city and goes through the panels to the tank. it doesn't matter with these types of systems if the sun is out or not, the water will flow through it. no electrical controllers. big tubes in the panel, about 3".

active, if there is a temperature differential from the solar tank and the solar panel then it fires up the pump to get water going through the panel into the normal tank. there are sensors and a controller near the solar tank. small tubes in the panel about 1/2".

the answer to your question is if the system is active or passive. Passive you can plumb into the tankless. Active you can't, it doesn't make any sense to.