Old Boiler - Trying to Control Water & Heating Independently

luckwudaveit

Posting on behalf of a family member. The boiler is a Baxi and must be about 40 years old. As far as I know, the water has always come on with the heating and vice versa. Recently, a control panel has been fitted to try and have independent control over the heating and water systems but it hasn't worked. The panel successfully opens the Honeywell valve, which is fitted to the hot water pipe that goes to a tank. When this is open, it also warms up the radiators. If I press the heating button on the panel, the boiler doesn't fire up. No room thermostats, but all radiator thermostats were fully up.
I have advised for now, to control room temperature using the radiator thermostats (but not all radiators have them).
Going by the photo below, can anyone advise if this set up can be retrofitted so that the heating and hot water can be controlled separately by a control panel?

FreeBear

Baxi Bermuda ?

Do you know what make & model the control is ?

Some will have a jumper or menu option for gravity hot water & pumped central heating. If we know what the control is, we can point you in the right direction.

As for improving the system and saving gas, a room thermostat and tank thermostat are essential. With a system this old, hard wired thermostats are pretty much all you can fit unless you go for a Drayton Wiser system (£150-£200).

I've also got a Baxi Bermuda - With a decent control system and thermostats, it is reasonably efficient and very reliable. Replacing it with a modern combi, whilst saving a modest amount on gas, the estimated savings doesn't make it an attractive proposition. That aside, there is hardly anything inside to go wrong, so repairs are hardly ever needed.

luckwudaveit

Thanks for the reply.

The flap inside the boiler says "Baxi WM 381 RS GC No. 41-077-05". Is that enough to go by? 

The newly fitted control panel is a Sangamo Choice PR2n - 2 channel programmer. 

FreeBear

OK, a wall mounted (nominal) 11Kw boiler - Basic, but still perfectly serviceable with a rated energy efficiency of 65%.

For the control, have a look at - https://cdn.shopify.com/s/files/1/1900/0799/files/Choice-PR2n-Install-Instructions-143793.pdf?16149532891351856755

There are some DIP switches on the back - Switch off the power, pop the panel off the wall, and move switch No.1 to Gravity. That should give you independent hot water without the central heating pump starting up. The radiators upstairs will still get warm with the boiler fired up to heat the HW - I turn the radiator thermostats right down during the summer months.

Have a look at fitting room/tank thermostats - You'll save quite a bit of money on gas, and the payback could be as little as a single winter.

luckwudaveit

Thanks very much for all of your help. I'll found out what the setting is and go from there, but I think it's in the right place, given what happens. (This isn't in my house, I'm trying to help someone out) 

fenwick458

luckwudaveit said:

Recently, a control panel has been fitted to try and have independent control over the heating and water systems but it hasn't worked. 

who fitted it, did they get paid? if yes then why as they have failed to do the job.
assuming they have used 2 x 2 port zone valves, and theres a programmer & stat for both HW and radiators, it's possible to wire up correctly so they are independent of each other

luckwudaveit

fenwick458 said:

luckwudaveit said:

Recently, a control panel has been fitted to try and have independent control over the heating and water systems but it hasn't worked. 

who fitted it, did they get paid? if yes then why as they have failed to do the job.
assuming they have used 2 x 2 port zone valves, and theres a programmer & stat for both HW and radiators, it's possible to wire up correctly so they are independent of each other

I'm a fourth party to this so don't know exactly what the trades person was asked to do. But as far as I can see, there is only one 2-port valve, on the HW pipe. If a second was fitted on the radiator pipe, will that definitely allow full independent control? I think it would. Also, what is a stat... Thermostat? 

Incidentally, I'm told the DIP is set to pumped and not gravity. But essentially, without a second valve, does this make any difference? 

FreeBear

luckwudaveit said:  what is a stat... Thermostat? 

Incidentally, I'm told the DIP is set to pumped and not gravity. But essentially, without a second valve, does this make any difference? 

"stat" - Short for thermostat. You'll often see "room stat" and "tank stat" which can be a little confusing if you are not familiar with the contractions.

Zone valves on a gravity system won't make any difference aside from adding a few extra wires to the mix. A single valve to the HW tank will help to divert heat to the radiators during the winter. Putting one on the radiator circuit would save going round turning off the radiators during the summer. Adds another point of failure to a very basic system though.

If the switch is set to gravity, then there may well be a basic wiring fault or possibly a duff switch on the valve. Without being able to poke at it with a multimeter, it is (almost) impossible to remotely diagnose the problem.

southcoastrgi

luckwudaveit said:

fenwick458 said:

Incidentally, I'm told the DIP is set to pumped and not gravity. But essentially, without a second valve, does this make any difference? 

Yes because if it's wired correctly then when it's set to gravity the pump won't operate on hot water