As usual, the posts at this time of the year are full of problems with these systems. Are there any advantages over the old idea of using a small header tank - other than saving the space, or where one can't be used as in some flats, etc?
If you get a leak (a) you know about it because of the drop in pressure; and (b) there's only so much water to leak out whilst you're away on holiday.
Easy to install, fill and bleed.
Less opportunity for the water to oxygenate, so less corrosion.
Eliminates any chance of "pump over" into header tank and resulting aeration, corrosion problems etc.
Phil
The full SP is in the FAQ. My view is that the advantages are pretty much conclusive. However if an existing system is open vented, correctly installed and working well, then there is no absolute need to change to unvented.
Are those the only reasons ? What are the disadvantages ? Rob
Based on discussions here and a visit to DPS I'm planning to install a GXV direct heatbank coupled to a Worcester 29HE boiler, so this will be vented. For a regular house without rads in the loft the disadvantages (expansion tank, pipework to the loft) don't seem to be so awful compared to the advantages (DIY, large thermal mass, efficient recovery, ease of maintenance) - what other aspects should I be considering?
Dave
If you're really worried about that, fit a stop c*ck. A normal system will last maybe two or more years before needing topping up. Servowarm didn't used to fit a cold supply to the tank at all - you just topped it up with buckets when needed.
... snipped
Now that seems a frighteningly simple solution! A low level warning device (floatswitch+buzzer) and a stopcock (normally off). Presumably there aren't any regs that would prevent this ... ?
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