Cleaning the Contacts

Occasionally, I install and/or troubleshoot thermostats for homeowners, but in every one of those previous cases they were for forced air natural gas systems. Since I started my business, I had a HVAC rider added to my insurance policy and kept it since a request that I receive every so often is to install smart thermostats. A request that I received yesterday was to troubleshoot a thermostat for a radiant floor heating system (along with replacing sink drains and hanging some large, fine art pieces). This was a first.

The issue with this thermostat is that when the up and down buttons were pressed, the temperature would not change without pressing them really hard. Even then, the temperature might change or it might not. The thermostat was installed in 2007, and this model is no longer manufactured. The homeowner did not want to have a newer model installed. Why? With the radiant floor heating system, there are at least four thermostats around the house and he did not want to mix makes and models of thermostats. New, old stock ones are available on eBay, and he purchased one, but it would take two weeks to arrive. The request was to see if I could fix the current one.

The batteries were taken out and the thermostat was removed from the wall. Luckily the manufacturer utilized screws to attach the circuit board to the face plate/front plate instead of plastic welding. Once the unit was separated, the contact points of the buttons were revealed. The contact points were cleaned, the thermostat was reassembled, and the thermostat was installed back on the wall. Guess what? It worked! It worked so well that the homeowner wants me to clean them all during my next visit since it is now the best functioning thermostat in the house.

One detail that should be noted when working on aging plastic products, like this one, is to take extra care when reassembling. The plastic was slightly yellowed, indicating that it is probably more brittle than when it was manufactured. When reinstalling the screws in an item like this one, I will spin the screws backwards and feel for them to drop into the original threads cut into the plastic. Then I will tighten the screws. If that is not done, there is a chance that the plastic will crack if new threads are cut, creating another problem.