Solar Water But Missing Cylinder.

Q: Our current house has a solar water heating system put in by a previous owner. Or rather, it has half a system. We have 8 large evacuated tubes on the side wall, a thermostatic mixer in the loft and a modulating combi boiler.. ..but there is *no* preheat cylinder. As far as I can see, this means the only benefit we get is that when we actually draw water the boiler gets really hot water from the underworked tubes (temperature limited by the mixer valve). So, not much help at all, really. No storage. Has anyone else come across this setup? Is it worth fitting a dual coil cylinder to add some storage to the system? If so, can it go in the loft? I've looked at the installation manual for the boiler and it can be set up to handle a cylinder as well as being used as a straight combi.

A: A dual coil cylinder implies that it is to be heated by the boiler as well as solar. Are you intending to re-arrange the hot water supply for better performance? Perhaps the cylinder doing bathrooms and the boiler a hot tap in the kitchen? Where is the boiler? If it is nearby then a single coil cylinder may be a better bet, with the water just heated by solar. Depending on the tubes, do you have information on the make, type and dimensions of the tubes, they may not be enough to heat a large cylinder. The options would then be a small cylinder or more tubes and a large cylinder. The rate of solar absorbtion in the uk is simply insufficient to give a throughflow system with the typical domestic size of panels. To gain a worthwhile benefit you must have some means of energy (heat) storage. My system is happily churning away at the moment 10.00 am, with the collector at 47 degrees and the bottom of my twin coil vented cylinder at 39 degrees C, top at 52 residual from yesterday. By early afternoon yesterday the collector was at 63 degrees and the cylinder at 58 degrees all the way to the bottom. In high summer the limit programmed for the cylinder is 65 degrees which would stop pumped transfer of heat. When that happens the water in the header of the panel would vapourise and the resultant steam cause that part of the primary water volume to be pushed back into the (20 litre) expansion vessel. The tubes are designed to look after themselves. When water is drawn and cold enters the bottom of the cylinder the sensor detects this and the controller restarts the primary circulation, cools the header and energy absorbtion resumes. I bought mine as a kit (Panel assembly, sensors, controller, twin coil cylinder) from an e-bay shop circa ?1000 but the impetus was a need to replace the old cylinder anyway. If you already have an evacuated tube panel you are about 40% there In your position I would install either an unvented twin coil cylinder or a vented conventional system again with a twin coil cylinder. If you go down the route of the vented cylinder you could retain the combi hot water outlet for the shower supply

Discuss It!

Most Popular Articles

More

Marketplace

Related Articles

More

Related Categories

More

Recently Added

More

You Recently Visited

Other Great Sites