Where to site fill and drain valves

[Trevor Jones]

I am trying to refill my system. I realise the best place for the valves is either side of the circulation pump but my pump is located close to the floor and I can't put a drain valve under it. I have put the fill and drain valves above the pump and tried to fill. A small amount of fluid went in then no more. There must be a blockage somewhere (assuming the filler pump is powerful enough).

My question is should you be able to push the fluid through the circulating pump in order to fill? If so I suspect the pump is jammed.

I have tried to remove the screw for the bleed valve on the pump in order to check but can't shift it.

Thanks,

Trevor

[LucMan]

Most pumps used for solar have an impeller that circulates the fluid. There should be no problem forcing fluid through this impeller. There may be an internal check valve inside the outlet of the pump that could be stuck causing your blockage. Check the model # with the manufacturers web site to confirm.
A fairly powerful pump is required to charge the system.

[Trevor Jones]

Thanks for the advice.

My circulating pump is Grundfos UPS 15-50. I can't find any reference to a check valve in the manual.

My filler pump is a Chinese effort a Bojin FL3210. It says it is rated at 100psi and I can't stem the flow with my finger when I try it with water in the garden. There must be a reasonable amount of pressure but I am not expert enough to know if it's sufficient.

[LucMan]

You need a pump that can pressurize the system to at least 50 PSI to be able to purge the air from the system in a closed type. Are there gauges, and a purge fill station on the system? Or is it a drain back system?

[Trevor Jones]

It's not a drain back system, it's a closed loop. There was no purge fill station on it. There is a flow meter above the circulating pump. I put in a Tee with a gate valve on it either side of that. I can then turn the flow meter to 0 so that the fill is forced up to the panel on the roof. That was the plan.

[Trevor Jones]

Finally managed to undo the vent plug on the circulating pump. The pump spins with a screwdriver as per the manual. Turned the power back on, looked through the vent and the pump was working.

Turned electric off again and undid a compression joint on the return from the roof panel (the one that was originally left undone). Air hissed out, then steam and then hot water started. Did it back up again quick! Tried the filler pump again and hey presto some fluid went in. Didn't manage to flush right round the system 'though. The filler pump got to it's max pressure and cut out.

Managed to release a bit of pressure by opening the flow valve. A little more fluid went in but not much. I think there must be quite a bit of air in there and the fill pump is just compressing it. Probably need to get on the roof and undo the bleed valve at the high point. Ah well, I don't have the equipment or the courage for that, Need to wait for the man!

[Mike90250]

If your system is stagnant and producing steam, it's not good. Cover the solar collector with some cardboard so it does not cook itself.

[J.P.M.]

If your system is stagnant and producing steam, it's not good. Cover the solar collector with some cardboard so it does not cook itself.

Add: Safety first. Make sure pressure and temp. relief valves are functioning properly and will lift as designed to relieve overpressure/overtemperature conditions before you fool with the equipment.

[LucMan]

There has to be an existing purge valve on this system, upload pictures if you can.

[Trevor Jones]

I think there is a pressure relief valve next to the panel on the roof. It's dark now. I'll get my camera and telephoto out tomorrow and see if I can get a picture. I had initially assumed this was an air bleed valve.

I can't find any other control valves on the system apart from what I assume is a flow meter that you see in the attached picture.

There was no existing purge valve. There was a fitting inline in the pipework that I think was undone to pump fluid into the system. This is to the left of the Tees and gate valves I put there to make my own filling station.

I'm hoping the steam I thought came out was just spitting fluid. It was hot but so was the fluid that came after. I can't recheck because only fluid now comes out of that join when I undo it. Strangely now it is cold!

I'm afraid the panel on the roof is out of my reach so will have to take its chance. Such a shame with all the sun at the moment.

Thanks for the advice and support I have received.
Pipework1.jpg
DIYPump1.jpg

[Trevor Jones]

Here is the gadget on the roof. I do know the temp sensor is dangling there. That is the next problem when the fill gets sorted.
RoofPanel.JPG

[LucMan]

The can on the roof is an automatic air bleed valve. These need to be replaced occasionally as they start to leak or get clogged.
You should be able to bleed the system from the 2 valves you installed.**** Turn the system off*****. Hook the pump up to the left connection, turn the screw ( connected to a butterfly valve) on the flow meter perpendicular (the barrel with the numbers ) to the valve to stop flow, hook another hose to the right valve fitting and put it in a bucket, put the left hose in the bucket of fluid that you are pumping in and pump fluid until it comes out into the right bucket with out any more bubbles. Close the valves, turn the screw on the flow meter horizontal, turn the system back on.
I'm sure there is another way that the installers filled and purged the system originally but nothing is visible from your pictures, possibly connected to the expansion tank.

[Trevor Jones]

Yep, I installed the two valves either side of the flow meter so that I could turn it off to direct the inflow to the panel. However, the fill pump cut out after a little while (it says it is rated at 100psi). I suspect as you say that the bleed valve is stuck and there is an air lock. Trying to fill now just compresses the air. Unfortunately I am unable to get on the roof so don't think there is anything else I can do. Unless.... do you think it is worth draining the whole system and trying again?

[Mike90250]

It looks like you have vacuum insulated heat tubes, that heat the water. with out water circulating, and sun on the tubes, they will get extremely hot and crack and fail, If I'm interpreting the picture you posted correctly.

[LucMan]

Yep, I installed the two valves either side of the flow meter so that I could turn it off to direct the inflow to the panel. However, the fill pump cut out after a little while (it says it is rated at 100psi). I suspect as you say that the bleed valve is stuck and there is an air lock. Trying to fill now just compresses the air. Unfortunately I am unable to get on the roof so don't think there is anything else I can do. Unless.... do you think it is worth draining the whole system and trying again?

The air should purge if the pump is supplying sufficient pressure and flow unless there is a restriction, (possibly a "check" valve that is stuck or gummed up). What did the fluid look and smell like when you drained the system to install the valves? You could drain the system and disassemble the check valve to make sure it is clean and operates freely. Glycol mixtures should be changed every five years on evacuated tube systems as it breaks down from stagnation temps of the the panel. Flush with clean water & Refill with solar rated glycol "only" (IE Romar Solarguard) as it is formulated for higher temperatures and resists breakdown.