To tinker or not to tinker that is the question!

[timsmedley]

I have just moved into a large house with a pumped central heating system, the boiler being a Potterton Kingfisher 2 which i believe is about 12 years old.

They have bastardised the mechanical Landis & Gyre timer so that to work the hot water you have to have both hot water & central heating selected. To switch the heating on, there is a seperate toggle switch on a home made box which effectively gives you H/w or H/w & C/H.

There seems to be no T-valve and a pump for each heating circuit. Both circuits disappear into the boiler, so i presume the boiler is designed this way.

There is a room stat as well as a h/w cylinder stat. I have added TRVs to the rads.

All works well, except that the timer is cumberome and allows only two time periods which have to be the same very day and have to be the same for H/W & C/H. The override is basically off/on until the next time period and in a house this size it is expensive to let it run.

Q1 Is the set up i describe normal - i.e. to have two pumps.
Q2 Is it possible to get an electronic programmer to control a 2 pump system?
Q3 Is it easy to do and under the wiring rules, are we amateurs allowed to do it?
Q4 If the answer to the above is yes, how about being able to add extra valves to split upstairs & downstairs into two zones, or am i pushing my luck?

Any help gratefully receieved.

Tim

 

[ChrisR]

Q1
Slightly normal. May have had HW pump added to a gravity circuit - expect it's on the return?

Q2
Standard ones will do it - if you wire it up right!

Q3
Some folk would find it trivial, others impossible...
If I were you I'd just get on and do it. That isn't advice, I'm NOT you!
Technically I think I'm right in saying you "must" test it - with kit you won't have.

Q4
Simple in principle, depends on the plumbing.

 

[Gasguru]

It appears a keen diyer may have set up your heating system as your setup is unusual, unfortunately he bodged it and didn't know how to finish the job.

However, Grundfoss pumps introduced a twin head pump a few years ago. The advantage is you don't require any zone valves/mid position valve. This Grundfoss "Pumpplan" also comes with a wiring box that takes care of the control of the pumps/boiler.

You choices are to keep the two pump setup, buy a standard twin channel programmer and devise a control system,

or

Go for a standard setup with a single pump and either a Y plan (mid-position valve) or S plan (multiple zone valves) setup.


If you decide to keep the twin pump setup check you have non-return valves after each pump outlet. If not you may find with hot water only on a few radiators warm up and vice-versa.

Next the hot water and heating live out from the new clock connect to their respective thermostats. Each thermostat switched live connects to their respective pump. Each switched live from the stats must also power individual relays (with a 230/240 VAC coil). The contacts of each relay will power the boiler. In this way you can have either hot water or heating enabled independently or together.