Large bubbles/low flow in Solar Pool Heating after Relocation

[webpool]

Hi all,

I recently relocated my solar pool heating setup from a flat roof onto a new pitched roof shed. I followed the layout I found on a solar site but when i turned it on was continually getting large bubbles in return and also low flow could be seen through the chlorinator. Changing variable pump speed didn't seem to make a difference.

My guess is that there is too much pressure/not enough flow getting through the first section and then this is resulting in low flow/air through the second section. Alternatively maybe I've created an airlock somewhere. Please see figures for the design i followed and a photo of my setup.

Really keen to get the forums feedback on design for the shed prior to spending another day on the roof moving things around.

Thanks.

 

[1poolman1]

It appears that the diagram and photograph don't match. The diagram shows a continuous feed pipe over the ridge. You are feeding the second set of the array from the return of the first. That creates a lot of restriction. The water is then falling off the roof faster than it can be supplied and is pulling the vac-relief open and pulling in air. I see this with all solar heating when the flow gets restricted, mostly from a very dirty filter or a VSP set too low.

 

[CRAD_oz]

Looks like it is piped as per the diagram.
Are the bubbles seen after minutes or hours?

 

[webpool]

Yep, as per diagram - feeding the second set of the array from the return of the first is what they've shown.

1poolman1 - is this not how you've seen it done in the past? I'd back washed the filter and tried VSP on high and didn't seem to change behavior. What you've described regarding restriction is what I thought might be happening.

I was thinking I could try just doing one feed for both arrays (see attached) which I believe is what you're suggesting but didn't want to go against the manufacturer without some guidance from the forum. It seemed odd that they went to the extra effort of showing the feeding of the second set of the array from the return of the first if there wasn't a good reason for doing so given it's a lot more hassle.

Bubble last as long as I've left it run >30min

 

[1poolman1]

Yep, these old eyes fooled me again. It is installed according to the diagram. I used to install solar arrays very similar to what you have. I don't remember the brand, but liked the ones I used as they had far less roof penetrations and were much less susceptible to freeze damage (though not completely).

They were always fed from one pipe or supply circuit and the return was another, separate, line. The way the diagram shows, you're feeding heated water into the second array. Maybe this is something new, but I have never seen it.

If you have no suction leaks that only leaves one place the bubbles (air) can come from when the solar is on, the vac-relief. Water coming off the roof faster than it goes up will pull that valve open and suck in air. I've seen that too many times to count.