Glycol heater system problems

[spareparts]

A new expansion tank was installed just a few months ago, last November I believe.

I'll look around on the roof and under the crawl space some more and see if I can locate a pressure relief valve. The only thing I've noticed so far is what I think is the air bleed valve, which looks like a copper elbow pointing up, with a plug threaded into it anand a bolt screwed in to the plug (best way I can describe it).

[inetdog]

There has to be some sort of pressure relief valve in the system, possibly draining in a way that hides what is coming out. That along with an inadequate expansion tank (possibly fluid filled by now instead of air filled) can lead to overpressure when the glycol expands causing a loss of glycol, then when the system cools even a small inward air leak can fill up the remaining space from the lost glycol. Instead of glycol returning from the expansion tank to fill the volume, air comes in and is not eliminated when the system heats again, causing the boiling glycol you saw when you tripped the air elimination valve on a hot day.

Bottom line suggestion, you have two problems:
1. Waterlogged (glycol filled) expansion tank and
2. A leak, possibly at a relief valve, that drains glycol where you cannot see it.

Draining the system and pressurizing it with air is one way to try to locate that leak.

[spareparts]

Any chance you have an air elimination valve on the top of the system?. They are known to leak.

There is a manual valve up top. I'll spray it with soap bubbles tomorrow and see if I detect any leaks. I haven't found any liquid glycol leaking out of it though, I have a flat roof and have checked top to bottom several times recently looking for leaks.

The nearest solar technician is 45 mins away, at his request I opened the valve at one point and steam was was coming out of it.

[peakbagger]

Any chance you have an air elimination valve on the top of the system?. They are known to leak.

[spareparts]

Hi, new to solar and have an issue with my glycol system. We bought our first home and a previous owner had installed a solar heating system.

There's three panels on the roof and two radiator type devices in two separate rooms in the house. Each has a fan and kicks on when it reaches temp I'm new to solar so if you need me to find specific info just let me know what will help out.

Problem I keep running in to is what I think is vapor lock. I have to have the system purged of air/gasses and filled up with about one to two gallons of glycol every month when the pump gurgles and won't supply hot glycol to the radiators. I can't find any leaks anywhere that would account for this missing volume.

Pressure starts out at 30psi when the unit is filled on a sunny day and steadily drops as the month goes by. Dial reads 10psi now, circulated enough fluid to turn on one radiator unit for about 5 mins and then stops...pump still running but no more heat.

Is it possible that the panels are overrated for this system, generating too much heat and boiling off the glycol? Should I cover one? Or cover, say the bottom or top third of all three?

Eventually we'll install another radiator or two but first need to have some double or triple pane windows installed and a few other projects around the house.