The Halstead Solar Hot Water package was indeed a package and arrived on a big pallet with the cylinder, three panels and the control pack. The kit is one of several options to suit various sizes of homes. The three panel kit is suitable for family homes with two bathrooms where hot water consumption is on the high side. After some careful measurements we decided that we could just about accommodate the new Halstead unvented dual coil cylinder in the airing cupboard.

We had just 5 millimetres to spare, or so we thought. Once we had the old cylinder stripped out and we could offer the new cylinder in we found that the cupboard tapered by 10mm. Moral = ‘if things are tight always check the dimensions in two places’. The only option now was to hack a little plaster out of both sides at the widest point. Luckily the plaster was old and practically fell off the wall and the cylinder slipped in to place like a space shuttle docking.

Luckily the incoming service was already 25mm, a heritage from the time that the property had been let as flats. There was also a lot of confusing redundant pipework leading to cylinders that no longer existed and we decided to rationalise it. This ended up taking a lot longer than we thought because all sorts of bits had been added and we weren't sure where they went. We wanted to convert the whole house to mains pressure and pressure balance the supplies by taking the cold off after the pressure regulator supplied with the cylinder. One slight unexpected problem we encountered with the higher pressure was that chrome pipe in the bathroom had been joined with push-fit fittings and though they had survived on the down service they would almost certainly blow on the mains.

Another detail on the plumbing that needed to be planned for was the possibility of the water temperature exceeding 60 degrees when the sun is hot. To eliminate any risk of scalding and to optimise the hot water usage we decided to fit a thermostatic blending valve TMV3 on the hot water outlet form the cylinder. I would like to see this supplied as standard with solar cylinders because it is always required. Unfortunately our merchant didn't stock one suitable for the high temperatures of solar so we had to order one. This delayed the solar hook up.

The cylinder proved easy enough to fit. Unusually Halstead uses stainless steel plain pipe instead of tappings. This means that there are no threads to damage but you need compression fittings. The pipe sizes are very tight and the olives just about went on with a tiny bit of tapping. Resist the temptation to tap too hard because the pipe will push the cylinder wall in if you hit it too hard.

Having done a good many solar and unvented cyclinder courses I was fairly at home with the technology, though it is always a bit more involved in a real situation rather than a class room. The instructions supplied with the cylinder and solar controls and panel are bad. I can't recall seeing worse instructions for a job of this nature. The obvious way to gain knowledge is from a training course but Halstead have to accept that these packages will be purchased by plumbers, and others, who have little or no knowledge of solar. A lot better information is required if serious errors are to be avoided. As far as the cylinder goes life is a little more straightforward but as a dual coil cylinder it would have been helpful to have some indication that the solar connects to the lower coil. The instruction supplied were for a single coil cylinder, hence no mention of blending valves or other considerations such as no using plastic on the solar primaries. A further complication was the fact that the 22mm discharge pipe had to be taken from the middle of the house under several floors before it could be terminated in a safe place. The pipe has to fall continuously so it can only run in between joist and not across them.

We were already running a day late on the cylinder and then just as we were gathering strength for the long haul up onto the roof a big thunder storm came rolling in. The customer now had hot water back on tap so it was possible to roll the solar hook up over. Unfortunately my mate was off on holiday and that meant a further delay. The problem with most panels is that they require two or even three people to get them up on the roof. There really is no need for them to be quite so large and the sooner panel manufacturers adopt a bit of technology from roof window manufacturers the better. Four half sized panels that push together would be infinitely easier.