More re-heat and more meters!

On comparing the performance of radiators with the heat throughput expected of the steel/plastic/copper structure it appears that, even though steel is 200 times better than plastic the heat loss by convection is still, by 10*, the major restriction. Consequently it should be fine to use the plastic grid as an external radiator for summer re-heating, subject to its uv resistance.

Of course we had a new meter installed as part of a change to 3-phase, and the installer described it as 'smart', though the suppliers (also eon) subsequently denied this. It appears, however, that the installer was correct and this meter is now described on the website (if one checks this specific installation) as 'able to be read using sms'. Photos clearly show that this is right. On the other hand the system of (e-mail) requested meter reads and occasional calling readers is still in place, and no remote reading is actually happening. The offered website 'energy tracker' just uses this monthly data. In fact the meter reading person has not even (on the second attempt) absorbed the idea that the meter is now in a box outside the house and he just leaves the usual card instead!

Note added 1/3/11
The meter was read by the meter man yesterday when we were out, but it appears that he inverted the day/night readings. So we have given two more (sets of) readings today which apparently allows this to be corrected. The meter does give 8 readings altogether, possibly associated with the potential ability to feed-in power.

Summer ground re-heating

Since the circulating fluid temperature for equal in and out (from the ground) now looks to be about 5-6 degrees, compared to 8-9 last autumn, there is significant ground cooling as expected. We could hope for this to even out over the summer by conduction or ground water movements, but for the borehole depths this might take centuries!

IVT do normally (in Scandinavia) do re-heating by circulating the fluid through an air heat exchanger (without power except for the pump and air fans), giving free air conditioning and, if most of the outgoing air from the house ventilation passes through (which looks hard) some efficiency gain. But this is a pretty expensive (>>£1k) option. It is also not well-suited to our system in which the GSHP is far from the bulk of the house. On the other hand it should be sufficient just to pump the ground fluid round and through an external (cool) 'radiator' in summer and let it heat up naturally. Any condensation would then just drip outside. Options for this (conventional steel being unsuitable for corrosion reasons) could be commercially-available Aluminium or stainless radiators, adapted compact ground loop grids from Ice Energy (?plastic) or a sufficient length of a grid made up specially of copper pipe (estimated some 15-30m of 38mm pipe might be needed). These could all be bolted to [the outside of] an outside wall near the GSHP and the flow re-directed with valves. The WEL should tell how well this works and we are trying to get power estimates from IVT, but a 'radiator' power of a few kW as normally reckoned (albeit for a larger temperature differential to ambient) looks about right to me.