anyone know how my central heating works?

Andy From Sligo · 06-01-2017 9:27pm #1

I have a room thermostat downstairs ... I have a Room thermostat upstairs. The Downstairs one turn on the rads downstairs and the upstairs room stat turns controls the upstairs rads - all good so far. but, I cannot see how it does it. There is a 2 way zone valve in the Hot Press upstairs but there is no actuator head on it, and I cannot find any other zone valves in the system anywhere else. Not even in the back of the outside boiler, and no more in the hot press - there has to be one hidden somewhere hasnt there? - theres no other way the upstairs rads can come on and off with the upstairs room stat without a zone valve can there?

Now also anther thing. The Immersion cylinder tank in the hot press is tied in with the rads, the upstairs rads it looks like, and heats up the water when the rads are on. In the summer I am still going to want to heat the water in the immersion cylinder by oil central heating rather than electric element, how am I going to do that. Will I have to go round turning off all upstairs rads and put the upstairs thermostat to 25c to heat the water or is there another ideal way?

Pete67 · 06-01-2017 9:43pm

There could be two separate pumps, one for each heating zone?

Andy From Sligo · 06-01-2017 9:57pm

Pete67 wrote: »

There could be two separate pumps, one for each heating zone?

can only find one circulating pump to be honest, the one at the back of the outside condenser boiler module

Tom44 · 06-01-2017 10:26pm

1 pump is normal.
Post photo of valve's

hatchman · 06-01-2017 10:49pm

Finding out how the heating works the down stairs and upstairs circuits is not going to solve your problem for the summer. Unless u are prepared to put in another circuit for the hot water cylinder what's your issue ?

Andy From Sligo · 06-01-2017 10:54pm

hatchman wrote: »

Finding out how the heating works the down stairs and upstairs circuits is not going to solve your problem for the summer. Unless u are prepared to put in another circuit for the hot water cylinder what's your issue ?

it was 2 separate questions ... but related , if you get my meaning

Andy From Sligo · 06-01-2017 11:56pm

I wonder if the immersion coil is plumbed in a way of that its a 'heatsink Rad' if it is then maybe I could turn off the upstairs room stat and the water still flow just through the coil in the immersion cylinder? - I must try it one day. Is that a possibility, do some heating engineers/plumbers do it that way?

antoinolachtnai · 07-01-2017 12:54am

Is it possible to have the rads on downstairs, but the rads upstairs off?

Follow up question - do you have and know how to use a phase tester screwdriver or another mains test device safely (there is no shame in saying you don't).

Andy From Sligo · 07-01-2017 1:36am

antoinolachtnai wrote: »

Is it possible to have the rads on downstairs, but the rads upstairs off?

Yes

antoinolachtnai wrote: »

Follow up question - do you have and know how to use a phase tester screwdriver or another mains test device safely (there is no shame in saying you don't).

Yes

antoinolachtnai · 17-01-2017 12:07am

My idea here was that gravity is feeding the upstairs and that the pump is feeding the downstairs. This does not sound right if it is possible to heat downstairs without the upstairs.

Gravity is a very old way of doing this stuff, but is not used anymore as far as I know. The water is circulated by gravity, well to be specific, the hot water is less dense than the cold water and this means the hot water floats to the top, pushes the cold water down to the boiler and so allows the water to circulate.

If it were gravity then the stat would be turning on the boiler but not the pump.

You might be able to figure out what is going on by using the tester to work out what effect the stats are having on supplying power to the boiler and pump. To do this you need to make a chart first of all of all the wires you can test and then see whether the wires are on or off in each of the four states the system can be in.

You may find it helpful to draw a circuit diagram of the parts of the system you can see.

This will give you some sort of clue. Taking a close look at the wiring after having done the charts might help you figure things out. Be careful, you are working with live voltages.

If it turns out to be beyond you the documentation you put together will still be helpful for someone else trying to figure out the system later.

Andy From Sligo · 17-01-2017 12:16am

thanks, if Gravity were involved would there have to be 28mm pipes in the system? - as far as I can see they are all 22mm pipes throughout apart from obviously at the rad/TRV end they are 15mm pipes

antoinolachtnai · 17-01-2017 12:44am

Yes, there are usually big pipes for gravity feed, though there is no law that says that there has to be 28mm to have gravity feed. If there is even a place for where an actuator head might go, it is unlikely anyway.

Is there any sort of back boiler on the system? How old is this house and system?

It does sound on reflection like there is a valve somewhere. It is certainly well worth finding out where the valve is if that is the case.

smjm · 17-01-2017 9:22am

I know you said you can have the rads downstairs on and the rads upstairs off, but does the opposite work, i.e. can the upstairs rads be on without the downstairs also being on?

jc500 · 23-01-2017 8:31pm

Hello I would agree there isn`t a zone valve for downstairs, just upstairs, and the missing head off the valve controls heating/hot water upstairs.

Andy From Sligo · 24-01-2017 12:48pm

smjm wrote:

I know you said you can have the rads downstairs on and the rads upstairs off, but does the opposite work, i.e. can the upstairs rads be on without the downstairs also being on?

I know for sure definitely that the upstairs rads can be on with the downstairs rads off, I know that for sure because when the downstairs room stat has reached the downstairs rads are cold but the upstairs ones are still hot. However I'm not 100â„… sure about the other way round I shall have to try it

antoinolachtnai · 24-01-2017 4:12pm

Check this for sure. Will tell us a lot.

Andy From Sligo · 28-02-2017 4:26pm

Hello - sorry for late reply.

OK, so I turned upstairs thermostat all the way to down (off) and went up an hour or 2 later and the radiators were still getting hot upstairs - so it dont seem like the room thermostat on the landing upstairs has no effect to turning the boiler on or off , the upstairs rads are on and heating then as long as the time clock in the kitchen is on . but the downstairs rads only come on when the room stat in the hall calls for heating and then go off when the room stat has reached.

So the way the plumber/heating engineer must have plumbed it up is that maybe the whole upstairs radiators and heating coil in immersion tank must be plumbed up in a 'heat sink' arrangement. Thats all I have come to the conclusion of .... but how comes the rads downstairs can come on and off independant of the upstairs rads when the downstairs roomstat calls or is satisfied when there are no zone valves anywhere (well there is a zone valve in the immersion cupboard hotpress upstairs but there is no actuator head on it - and in the back of the outside boiler there are no zone valves fitted just your normal CH pump and frostat)

EDIT: I looked inside the upstairs roomstat and all the wire connections are made to it - so there is none missing nor a link wire put in place

antoinolachtnai · 28-02-2017 4:47pm

My guess is that the upstairs stat turns on the boiler only. The downstairs stat turns on the boiler and the pump.

If the boiler is on but not the pump, only the upstairs heats. This is because hot water rises.

If the boiler and pump are turned on, the hot water is circulated to the entire house.

Andy From Sligo · 28-02-2017 5:05pm

antoinolachtnai wrote: »

My guess is that the upstairs stat turns on the boiler only. The downstairs stat turns on the boiler and the pump.

If the boiler is on but not the pump, only the upstairs heats. This is because hot water rises.

If the boiler and pump are turned on, the hot water is circulated to the entire house.

ah right thanks , that does make sense - so my next project then (when weather gets better) is to take back off boiler and listen to pump with downstairs stat satisfied and see if pump is off but still heating upstairs rad then . I shall do that one day.

And with the boiler firing but without the pump going (if this were the case) would their not be overheating/boiling issues? - I thought on these boilers you had to have the pump running same time when the burners are firing up? no?

antoinolachtnai · 28-02-2017 5:29pm

I could be wrong about the setup.

What kind of boiler is it? Is the pump integrated in the boiler? How old/new is this installation?!

It won't overheat unless it develops a fault. The boiler stat will just knock off if it gets too hot. If the water can circulate, by gravity or otherwise, the heat will run. Even if the boiler stat were to fail, as long as it is an open system with a feeder tank in the attic, it won't really get dangerous (though the house might get very hot and there might be a good bit of steam in the attic).

I am not recommending this as a way for having heating set up by the way!

Andy From Sligo · 28-02-2017 5:46pm

antoinolachtnai wrote: »

I could be wrong about the setup.

What kind of boiler is it? Is the pump integrated in the boiler? How old/new is this installation?!

It won't overheat unless it develops a fault. The boiler stat will just knock off if it gets too hot. If the water can circulate, by gravity or otherwise, the heat will run. Even if the boiler stat were to fail, as long as it is an open system with a feeder tank in the attic, it won't really get dangerous (though the house might get very hot and there might be a good bit of steam in the attic).

I am not recommending this as a way for having heating set up by the way!

Its a grant ecoflame outdoor boiler unit with integral CH pump at back and the pipework is all 3/4 fitted in 2012 according to the grant paperwork left in a drawer and house built in 2008- yep open system with combined FE with tank in the attic and the outdoor boiler unit has a 1bar (or is it 2 bar) pressure relief valve on the flow connection so it should be OK and yes the boiler stat in the housing is dual stat with overtemp reset.

Yep, strange unorthodox setup it sounds like - I can understand if it had diverter zones with actuator heads diverting to upstairs or downstairs rads

antoinolachtnai · 28-02-2017 5:56pm

The wiring would need to be a bit 'custom' in the boiler to do this arrangement. I do not think the manufacturer would not be too impressed because it would mean that a separate supply was running to the boiler. Maybe the manufacturer allows this, but I'd be surprised. A look at the wiring would tell you pretty quickly.

Funny enough that the boiler was replaced or installed four years after the house was built.

The gravity feed business is the sort of thing I would expect to find in a house from the 70s or maybe the 80s, not from the last ten years so I wouldn't be altogether surprised if we are wrong and there is an actuator valve somewhere.

anyone know how my central heating works?

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