Does the boiler instructions say anything about where the vessel should go? If so they 'trump' any requirements of BS 6798.
If the system pressure is reasonable (1-1.5 bar) then even if the pump came before the vessel then the reduction in circuit pressure would not be that significant.
On Sun, 16 Jul 2006 10:50:22 +0100, Lobster wrote (in article ):
Think about an open vented system. The relief vent is generally two floors at least away from the boiler. This doesn't cause a problem.
Not quite.
That example is of a sealed pressurised water cylinder where the bulk water in the cylinder is the DHW - in the video heated electrically.
The nearest to this would be a similar arrangement, possibly with immersion, but also a coil heated by water in the primary circuit of the boiler. Part G of the Building Regulations applies. If you look at the installation guide for the UK of a typical pressurised cylinder, (e.g. Albion), it shows an expansion valve on the cold feed and a pressure and temperature relief valve on the hot side.
However, in the case of a loft tank fed storage cylinder, the cylinder contents are not at mains pressure. The coil is at sealed system pressure. If a problem happens with that such that the pressure relief valve blows, water will be discharged from the primary circuit and not replaced. This is not likely to result in the cylinder exploding.
The same would be true of a heatbank or thermal store. The bulk water in the cylinder may be heated by the boiler directly or indirectly, but is open vented
It does. The water in an open vented system is constantly rising up and down. It boils over at 100C. In a pressurised system the boiling point is higher, when it does go it is over 100C. Also there may be a weak point in the system. This weak point might blow inside the house casuing serious injury before the remote relief valve opens. You have the relief valve "on the boiler" or within a few feet of it.
Yep. BS are recommendations, unless pointed to by the buildings regs, which are law. The maker can overrride BS. But they can't go against the building regs.
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