Boiler/Heating System Help

the4horsemen

I've just moved in to a new house which is approximately 7 years old. I'm having a little trouble understanding and also working the boiler, heating and hot water.

It is setup as follows -

Boiler in the kitchen which I've found out is a heating only boiler.
Unvented hot water cylinder in airing cupboard on 2nd floor

To turn the boiler on I must turn on a switch next to the cylinder and also a switch next to the timer control unit adjacent to the boiler

There is a switch labelled water heater in the kitchen and another switch next to the cylinder which when turned on has 3 red neon lights above it?

I believe the hot water cylinder has an immersion heater also but I'm not sure if this is the primary source of hot water or a backup?

When I turn the heating function on the timer switch to on and turn up the thermostat the boiler fires up and the radiators heat up.

When I turn the hot water function on the timer switch to on the boiler fires up and I can hear the cylinder filling but the water from the taps is cold.

When I turn the water heater and the other switch with the three lights to on (although seems to work with either one) the water heats up from the taps. I assume this is the immersion working.

System

You seem to have a very odd set up. Most unvented HW systems have 2 in-line motorised valves in the airing cupboard to control the boiler flow to the heating coil in the cylinder and to the radiators. The HW in-line valve is controlled by a timer switch (Google Tempus 7 as an example) and a cylinder thermostat (to control how hot the water gets). The CH motorised valve is also controlled by the timer and, at the very least, a single room thermostat. There should be no need to use the HW cylinder's immersion heater. ( my gas costs me 3p per KWh compared to 11p per KWh for electricity so it is sensible to use gas if you can for water heating)

You could do the following:

a. Get to know your neighbours and ask them how the system works for them.

b. Call a heating engineer to check that all is as it should be. He/she can then explain how the system should work. The law is pretty strict on which engineers can work on unvented hot water systems so I would recommend a look at the Gas Safe Register to check that the engineer has the necessary unvented system G3 approval.

You also need to check whether your unvented cylinder tank needs its air-gap recharging. This does't require an engineer but you do need to know what you are doing. I re-charge mine about once a year. The air-gap ensures that there is HW pressure during periods go high demand; e.g.; 2 people having a bath/shower in different rooms at the same time.