Pressure Loss in Solar Thermal Systems

[Centralheatking]

One of my plumbing customers experiences a gradual small leak of the
heat transfer liquid over a month or two.

Eventually it stops working and they have to get it re-pressurised by
their installer - its several years old now and they say the liquid is quite
expensive. Is this usual and can they put any type of leak sealer in.

centralheatking :santa_smiley: UkPf Father Xmas 2012 ( I think)

 

[townfanjon]

The obvious question has the system been checked for a leak ? Roof maybe !!!
Does , or has the prv had to open? .
I would defiantly check the expansion vessel.
A mega long shot would be a leak on the coil in the cylinder

 

[Centralheatking]

I suppose I was asking a general question about
low pressure problems experienced with pressurised
Solar thermal systems - is it a usual problem ?

centralheatking

mn

The obvious question has the system been checked for a leak ? Roof maybe !!!
Does , or has the prv had to open? .
I would defiantly check the expansion vessel.
A mega long shot would be a leak on the coil in the cylinder

 

[townfanjon]

I am no expert on solar, but you should nt leak any HTF.
Usual iffs and buts like has this just started, has it been ok from the start. etc etc

 

[Ch4 plumbing]

Might be a finger vent on the outside of the roof leaking?

 

[Worcester]

1) yes you need someone that knows what they are doing, it shouldn't need topping up every couple of months.
2) the fluid should be replaced every five years or so, depending upon the size it will cost between £60 and £100 plus VAT at trade price
3) systems shouldn't need "constant" topping up, however they should be checked annually and serviced properly every 5 years, it is not uncommon to have to re-pressurise them each year, and it's a simple, though tome consuming job, and you need the right equipment.
3) on older system we regularly see small leaks / 'weeps' that have opened up over the 5 years (systems can get up to 160° C..) it is a right pain to fix as you have to strip quite a lot out to fix them, - and you can't use normal solder, so we use either solar rated xpress or compression (with brass olives)
A full service can easily take a whole day to do properly, especially if there is a weep or leak to fix.