BobRK

I have an old MYSON Velaire 110/135 oil fired boiler with a CL6 PO117 thermostat which has failed. The only supplier I could find on the internet says they are no longer available and there is no alternative. The thermostat adjustable knob on the front panel, see photograph, sets the water temperature. When the water reaches the temperature setting the thermostat opens a pair of 240 volt electrical contacts and the boiler switches off. A very basic form of control really. Does anyone know of a thermostat that I could use as a replacement? Thanks for reading.

Hi JohnMo, Many thanks for your continued interest. Apologies for the long delay: holiday and family issues have taken up a lot of my time lately. Difficult to get a full view of my hot water tank due to the width of the landing. However, the photo shows (from the top) boiler feed, boiler return (both grey lagged), solar heating feed, solar heating return (both black lagged) and the copper cold water feed from the cold water storage tank. Just above the solar heating return is the black cable from the tank temperature sensor. NB: the white sensor to the right controls boiler. The solar heating pipes run horizontal for approximately 40 cm and then vertically up to the solar heating pump station. As mentioned previously there doesn't appear to be a non-return valve anywhere. The most convenient place to install a NRV would be in the vertical piping inside the airing cupboard but are such fitings available and would this be the best position to install them? Any further help/comments would be much appreciated. Thanks.

Hi JohnMo and Redbeard, Many thanks for your interest. My hot water cylinder is a traditional one. Its about lagged 200 litres cylinder with an immersion heater a little under half way down the cylinder. there are 2 heating coils: the top one heated by the oil fired boiler and the bottom one is the solar heated one. The solar heated coil is just above floor level. The solar heater manifold is approximated at the height of the upstairs ceiling with pump station approxiamtely 1 metre above the mainfold. Due to the roof levels and the house design the pipes from the manifold drop first down about a metre, run horizontally through a cavity wall and then rise back up to connect to the pump station. If there should be a non-return valve where should it be position? I think a 2 port valve would do the same job as a non return valve but again where to position it and how connect it to the controller? Thanks again for your interest.

Hello, I have a Kingspan Thermomax solar heating system installed which works well. It comprises a 20 tube array on the roof, a Dual Stream pump station in the loft, an SC100 solar controller and a 200 litre hot water cylinder in the airing cupboard upstairs. However, overnight the temperature at the bottom of the hot water cylinder goes down until it is just 2 to 3 degrees higher than the manifold temperature on the roof. This happens irrespective of the outside air temperature. Consequently, our supply of hot water disappears quicker than it should. It looks like the system is syphoning heat from the bottom of the cylinder to the manifold until there is enough daylight for the system to start producing heat again. So far I have found that the pump is NOT running overnight, there doesn't appear to be a non return valve anywhere unless there is one in the pump station and the controller correctly displays the temperatures at the manifold and at the top and bottom of the cylinder. Any thoughts on tests that I could run, possible causes and/or changes I could make would be very much appreciated. Thanks for your interest. BobRK.