Hot water | Leaking TPV / expansion vessel

donal.hunt

system type: Unvented solar indirect dual coil + immersion hot water cylinder...

Seems I either have a failing TPV or a failed expansion vessel. Had a local company out to inspect it and they are recommending to replace the TPV at the top of the 300L cyclinder, the expansion vessel and group set.

Current parts seem to be:

• CALEFFI SERIES 309 (P/N 309470 CST)
• ZILMET 110-ULTRA-PRO DESIGN Nᵒ 20014
• CALEFFI 533002 CST

What's a ball park for how much it should cost for parts and labour for the replacement in the Cork City area? Feel free to DM (I think that's the recommendation from the charter).

Also - looks like the expansion vessel is plumbed directly to the hot return of the cylinder. Had a look at some schematics online and it doesn't seem very common (usually connected off the group set). I can't figure out the model of the cylinder (label was removed. grrr.) and it doesn't seem to correspond to anything I can find online. Looks like it might be a Joule cylinder but current models have a different layout. Any comments / insight appreciated (I don't get plumbing but interested to a least vaguely understand what's going on).

John.G

As you say, the EV is normally plumbed from the group set but from a expansion point of view will work perfectly well from the cylinder outlet but will run hotter.

Re EV failure, you can do one or two simple tests yourself, one, just remove the plastic cap on the end of the EV and press the schrader valve (car tyre type)with your finger nail and see if air or water comes out, if air, then not failed but may need re pressurizing, if water, failed, if no pressure, not failed but needs re pressurizing. The group set has the PRV set to 3bar and the expansion (relief) valve set to 6bar, the TPR valve is set to lift at 7bar so the expansion valve should lift before the TPR valve.

Does the TPR still leak/dribble if you run off 4 or5L of water?.

Also if the EV has failed then the expansion valve should lift every time you reheat the cylinder.

John.G

This is a schematic of normal EV connection.