Plumbing – Combi boiler chemical replacement

You've bought a programmable thermostat so you can lower the temperature of the house at night, however by doing that you are making it much harder work for the boiler to bring the house back up to temperature. Before your house was at a constant temperature so you boiler would turn on for a bit, off for a bit, on a bit, off a bit over the whole day. Now it goes off for a long time and your house gets cold, then it has to run a very long time to get it back up to temperature again, leading it to overheat and shut down.

It may be your boiler simply doesn't have the grunt to heat your house for that long. Try setting your night-time temperature a bit higher and see if that improves the situation.

It could also be that your system is gunked up, leading to poor water circulation in your system. Did you have your heating engineer put a cleaner in the system? If not, have him try it.

You should make two phone calls. The first to your local building department, which should be able to answer all your code related questions. They may even have a handout or other documentation, that outlines the requirements of replacing a water heater.

The second call should be to a local Rheem dealer, or directly to Rheem. They will be able to answer any questions you have about the equipment.

Some things to watch out for:

• Make sure you drain the old tank completely, as water can be quite heavy.

• When draining the tank, make sure you open the hot valves at fixtures. This will allow all the water to drain back to the tank.

• When opening valves at fixtures, watch out for mixing valves. These can accidentally backflow cold water through the hot water pipes, which would lead to an undrainable tank.

• If you have to install an expansion tank, make sure you charge it properly.

• Make sure you know where to dispose of the old tank, as some municipal garbage collectors will not take water tanks.