Help with mysterious air in the line when using solar heater

[BurnChar]

I read that if my pump is spewing out bubbles, that there must be a leak in the piping leading to the pump's input, because those pipes try to suck in surrounding air. My system has bubbles, but not from there.

• When I out to the solar heater on the roof, there are tons of bubbles at first, but still quite a few hours after settling.[/*:m:3e9s6k7v]
• When I bypass the heater, there are no bubbles.[/*:m:3e9s6k7v]
• The inputs to the pump do not change in either case.[/*:m:3e9s6k7v]

Below is a photo of my control system. The 3 valved pipes coming up from the ground feed the pump.
When I divert water through the solar heater (on roof in a photo later in this thread), I get bubbles, but that is a pressurized line -- it is forced water FROM the pump. Where could they possibly be coming from?

I have no water leaking from the roof or the piping leading to it. Being pressurized, wouldn't it leak water rather than taking in air? I don't get it. Any ideas on how to diagnose this are appreciated.

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Edit: Updated photo and clarified post

 

[jblizzle]

Re: Help with mysterious air in the line when using solar he

Welcome to TFP!

Check the vacuum release valve on your solar system, on rare occasions these can result in air drawn into the system on the roof.

You could check this possibility by temporarily removing it and installing a plug. If the bubbles go away, then you will need to get a new release valve.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[Isaac-1]

Re: Help with mysterious air in the line when using solar he

Also where is your vacuum release valve located, is it at he highest point on the solar panels or mounted somewhere lower?

 

[bobodaclown]

Re: Help with mysterious air in the line when using solar he

Air in the system would have to be on the vacuum side not the pressure side. Maybe it's residual air in the solar piping, getting into the system when you shut down.
Any air in your basket?

 

[mas985]

Re: Help with mysterious air in the line when using solar he

Most of the time an air leak is on the suction side of the pump with two exceptions.

1) Backwash valves can sometimes allow air into the filter when a pump is off.

2) A vacuum release valve in a solar system can also draw air under certain circumstances. This usually happens with a high installation and a dirty filter but it is because the pressure at the VRV is below atmospheric so there is a slight suction.


Questions:

What is your clean filter pressure and what is the current filter pressure?

What is the height of the panels relative to the filter gauge?

Have you tried backwashing the filter? If not, try that first.

 

[BurnChar]

Re: Help with mysterious air in the line when using solar he

Air in the system would have to be on the vacuum side not the pressure side. Maybe it's residual air in the solar piping, getting into the system when you shut down.
Any air in your basket?

I see a few bubbles popping around in the basket when using the solar heater, but no air pocket develops. I suspect the bubbles rush by too quickly to see most of them.

 

[BurnChar]

Re: Help with mysterious air in the line when using solar he

Welcome to TFP!

Check the vacuum release valve on your solar system, on rare occasions these can result in air drawn into the system on the roof.

You could check this possibility by temporarily removing it and installing a plug. If the bubbles go away, then you will need to get a new release valve.

Posted from my Droid with Tapatalk ... sorry if my response is short

Thank you for the welcome. I always look for forums with very knowledgeable people and this was clearly the one for pools.

I have only from your reply learned of the existence of release valves. I'll look for it on the roof today. Thank you!

 

[BurnChar]

Re: Help with mysterious air in the line when using solar he

Also where is your vacuum release valve located, is it at he highest point on the solar panels or mounted somewhere lower?

I've never seen it, so I assume it's on the roof (if it exists at all -- the previous owner liked to take short cuts).

 

[BurnChar]

Re: Help with mysterious air in the line when using solar he

Most of the time an air leak is on the suction side of the pump with two exceptions.

1) Backwash valves can sometimes allow air into the filter when a pump is off.

2) A vacuum release valve in a solar system can also draw air under certain circumstances. This usually happens with a high installation and a dirty filter but it is because the pressure at the VRV is below atmospheric so there is a slight suction.


Questions:

What is your clean filter pressure and what is the current filter pressure?

What is the height of the panels relative to the filter gauge?

Have you tried backwashing the filter? If not, try that first.

My filter pressures are 12/13 (I recently backwashed).

The panels are probably 30-40 feet above the pump. They are on the house roof in the photo below:

 

[jblizzle]

Re: Help with mysterious air in the line when using solar he

Wow. That is quite the required rise to pump the water up to the solar.

 

[mas985]

Re: Help with mysterious air in the line when using solar he

12 PSI - 40 / 2.31 = -5 PSI at best

The panels are under a partial vacuum so air is probably being sucked in at the VRV. The panels are probably not primed either which means the flow rate will be very low through them.

You may need to downsize the pool returns to get the pressure up or re-plumb the VRV at a lower location.

 

[BurnChar]

Re: Help with mysterious air in the line when using solar he

12 PSI - 40 / 2.31 = -5 PSI at best

The panels are under a partial vacuum so air is probably being sucked in at the VRV. The panels are probably not primed either which means the flow rate will be very low through them.

You may need to downsize the pool returns to get the pressure up or re-plumb the VRV at a lower location.

I think I found the problem, and I am pretty sure there is no vacuum release valve:

The orange seems to be "Great Stuff" foam spray, used to "seal" part of the solar heater. Air is being sucked in and water slowly leaks out. Another surprise from the previous owner. Boo.

 

[mas985]

Re: Help with mysterious air in the line when using solar he

Other leaks can also cause the problem but the VRV is probably in the end cap of the header (three hose clamps). There are multiple implementations of VRVs. Look at the end of the header and you may see a screen which allows air into the header. With panels that high, I doubt it would not have a VRV. It might look like this:

 

[BurnChar]

Re: Help with mysterious air in the line when using solar he

Other leaks can also cause the problem but the VRV is probably in the end cap of the header (three hose clamps). There are multiple implementations of VRVs. Look at the end of the header and you may see a screen which allows air into the header. With panels that high, I doubt it would not have a VRV. It might look like this:

As far as I can tell, there is absolutely nothing like that in the system. All the ends are solid plastic.
When I replace the panels eventually, I'll have to add one.

 

[ed65roc]

Hi-

I'm moving this post as other thread was about constant bubbles and VRV.

I have a new Heliocol system and I too have a lot of bubbles each time the solar valve opens, and when the pump shuts off I can hear the VRV sucking air to allow the panels to drain. I have low flow rates due to a long plumbing run from the pool.

I must be missing something, as I would expect that the purpose of the VRV is to LET air into the system to break the vacuum. Perhaps I'm misunderstanding something. Are the bubbles an issue? I live in CA, and there is little risk of freezing; perhaps I'll just remove the VRV?

Last, I dont have a slope (left to right) to the panels and I wonder if there was the potential to put in an air escape valve to prevent air entrapment from preventing the array from filling properly?

Thanks all.