Brentford Heat Transfer Unit HTU Repair I don’t usually work on these, but the client was desperate as their usual engineer wasn’t available until a weeks time. So the tenant didn’t have Central Heating and we agreed that I would have a look. After looking at the unit, I found that there was no pressure in the apartments Central Heating Circuit and I Had to make a filling loop as there wasn’t one available. After I had re-pressurised the system, it still wasn’t working! I did some electrical tests and found that the Actuator was at fault, which stopped the system working. I didn’t have a replacement and as I knew it would only be a few days until the engineer arrived I left it off. This allowed the tenant to have Hot Water & Central Heating, which was on very cold week.