What is it

Big Will

These two tanks are installed parrallel with the solar collecter return piping. I have never seen anything like them and they have no numbers or manufacturer info on them. They have factory brazed and painted Ts top and bottom and they T top and bottom of of the solar return line. I can find no expansion tank in the system but I doubt this is it. If any thing they look like they could give the system some thermal mass. I guess they could be used as open expansion tanks if the top pipe was not tied in. One of the collectors ruptured and I think it is due to high pressure because of the lack of expansion tank. The adjustable pressure relief valve is set at 180 psi. 

Charlie from wmass

In wells there are horizontal tubes

That were sold so you did not need an extrol tank to cycle the pump. I would guess they are along that idea. But I do not do much solar. You may want to post this on the solar section of the forum.

Jamie Hall

Years ago...

(like 40!) I remember Jacuzzi sold contraptions which looked sort of like that.  They had a heavy wall rubber bladder in them, which could expand and contract slightly at the rated pressures to absord a small amount of expansion (or, in the case of these Jacuzzi whatnots, pressure change).  Could these be along those lines?  I also remember that they didn't work for beans...

Brad White

My guess would be

a coaxial heat exchanger. We see these on pools but also that take refrigerant hot gas (waste heat going to a condenser outside) and using it to pre-heat domestic hot water. Mueller makes these heat reclaimers and we specify them on kitchens were there are concurrent refrigeration and domestic hot water loads.



But in this case I suspect it is solar glycol pre-heating the domestic HW.



Anyway, my guess, I cannot see them that well.

icesailor

Looks like a hot water storage tank

They look like hot water storage tanks to me. If they are in Massachusetts, and are storing hot water without meeting Chapter 142 Regs, they are illegal. And they certainly aren't protected if the "adjustable relief valve" is set to 180#. That's some serious pressure. Is that so it doesn't steam? What happens if yo open a faucet and the pressure drops below the boiling point? GoBoom? How exciting.

solradman

may be a drainback reservoir tanks

We use similar looking tanks for some of our drainback systems.  Ours are 4 ft long by 5 1/2" in dia. with 3/4" male adapters on the ends.  Tanks come with 1/2 armiflex insulation around them.  I'm told they hold 2.5 gallons each.  Got them from Sunearth in Calif.  Picture included.

Mark Eatherton

I agree with Brad....

There use to be a company that had coaxial heat exchangers (4 ports per) that used silicone as their heat transfer fluid, and the exchangers looked real similar to those. If each one has 4 ports (2 gozintas and 2 gozoutas) then it IS a heat exchanger.



If each one one has one gozinta and one gozouta, then it is just a fat spot in the line, and is meant to act as a drain back reservoir/expansion vessel.



Hard to tell from the photographs how many ports each one has. If they are 4 porters, then there should also be a pump to move the potable water across the heat exchanger to move the heated fluid to the storage tank., and one to move fluid through the collectors.



If they are 2 porters, and there is a heat exchanger IN the storage tank, then they are just fat spots.



ME

Big Will

Drain back

makes sense. given the other mistakes made in the piping and design. The solar piping is set up for closed loop with p valve set at 180 psi. I should be able to add a air vent high in the piping and make it work as a drain back.

Big Will

Drain back

makes sense. given the other mistakes made in the piping and design. The solar piping is set up for closed loop with p valve set at 180 psi. I should be able to add a air vent high in the piping and make it work as a drain back.

Mark Eatherton

Don't do it....

Adding an air vent to a drain back system is a no no. You would NEVER be able to establish a siphon.



If you have to do it right, start from scratch, using proven technology and devices.



There is no right way to do things wrong.....



ME

Big Will

I laughed

The last line is great Mark.



The first thought to my mind was that there is a million ways to do it wrong. I guess it would be easier to set it up as a glycol. All I need to do is add a ex tank,air vent and a Fill/purge valve set. I have never liked the drain back idea any way.