Do i have an actuator?

[billy1666]

Just moved in to a new place, it has a glowworm space saver Mk2, controlled by a Siemens rwb2 timer.

If I turn the heating on from the timer, the pump starts up, but the boiler doesn't fire ( pilot is on but just sits there) and rads are stone cold.

If I flick the water on, boiler fires up instantly. The rads are hot when the water is on, whether the heating is on or off at the controller.

I instantly thought ah the actuator is stuck, however I can't find one!

Timer is mounted on opposite side of wall to under the stairs, so can see the cables on the other side. There is a cable going into a fused spur switch for power, one that goes off into the boiler, and one that goes upstairs to the CH pump which is under the floor on the landing.

I've pulled up a few boards to follow the water/ rad pipes but can't find a valve. Not in airing cupboard either. Normally i would just keep pulling boards and hope to find it, however its got me thinking, if there's no cable running from the timer, and there is a cable going in to the pump but none coming out, could it be that I don't have one, or is this normal?

Could it be I can't have the heating on without the water, and someone has just fitted a dual timer?

I'll admit I'm not 100% clued up, but id expect to find the valve by the pump (which is pretty much exactly above the boiler) or if not at least see an electrical/signal cable running somewhere.

I don't want to pull the house apart looking for something that isn't there?

Heating system pretty old (timer been updated at some point) so its definitely not going to be wireless!!

 

[ianmcd]

have a look at your hot water tank and if there are 2x 28mm pipes (1") going in and out at the side of the cylinder then most likely you have a gravity hot water system so wont have what you call an actuator, if these pipes are 22mm (3/4") then you do have zone controls either y plan or s plan again what you call actuators, the actuator is the motorised head that is fitted to either a 3 port or 2 port valve

 

[billy1666]

Thanks very much, I will take a look when I get home, so if they are 1" then I probably don't have control over whether I use heating, water, or both?

And if they are 3/4" then there must be a valve somewhere and I should just keep pulling boards and following the pipes?

I just find it strange that the central heating switch turns on the pump, but the water switch turns on the heating and the water, why would you ever want the pump to run but not the heating?!!!!

 

[ianmcd]

if your timer/programmer allows you to switch the CH on without the HW coming on and it is fitted correctly then you have a fully pumped system which must have some sort of zone control (actuator as you call it) if when you switch the CH on the HW comes on at the same time you have a gravity HW system and no zone control, depending on which system you have I will be able to advise you what the problem is, it is an external control problem and not your boiler but untill I know which system you have I cant advise what is wrong

 

[billy1666]

Thanks very much for taking the time to reply. Looking at the set up I do assume its zone controlled, but I'm just a bit confused where the valve / actuator will be!

Ok so I have a cylinder in the airing cupboard with 4 pipes

A 1" pipe that runs from the cold tank in the loft to the bottom left of the cylinder (reduces to 3/4" to connect to cylinder )

From the bottom right of the cylinder a 3/4" pipe runs out and under the floor, presumably the hot water "out" pipe

There is a 3/4" pipe going into the very top of the cylinder, which goes into the loft and curls over the feed back into the cold water tank

Finally there is a 3/4" pipe about half way up the cylinder, this reduces down to 15mm in a tee, which goes up into the loft, then tees into the bottom of the smaller CH header tank (ie the feed) and also upwards and curls over into the top (return / overflow)
The other end of this (where it tees near the cylinder) goes down into the floor, presumably the central heating hot "out" to the rads

Hopefully this is enough for you to identify it! (Although maybe I've just answered for myself as it looks like the tad water is being heated in the cylinder?????)

 

[45yearsagasman]

Why don't you post pics, it will save a lot of guessing as to what you have.

 

[ianmcd]

switch the HW on at the programmer on its own and see if the boiler fires then check to see if the pump is running at the same time

 

[billy1666]

Sorry can't post any pics, haven't got internet sorted yet and camera on phone is cracked!

Just tried, the pump only comes on when heating is selected
Just water - no pump
Just heating - pump is on
Water and heating - pump is on

 

[ianmcd]

hi Billy OK you have a gravity Hot water system but when your programmer was replaced whoever replaced it has set it to fully pumped, basically with gravity hot water you cant have heating on its own so the programmer has to be set to gravity, you dont have zone control, you can either make sure that HW is manually switched on when you want the CH to work or you have to remove your programmer and set it to 10 programmes instead of 16 which it is currently set, sounds complicated but extremely easy to do but make sure you isolate the power before attempting to remove the programmer.

here is a link telling you how to do this

http://www.industry.siemens.co.uk/b...l-controls/documentation/Documents/rwb2_i.pdf

 

[billy1666]

You sir are a legend thanks for being so patient and helpful. Ok so we can have water, or water and heating, makes a lot of sense the way its set up. So when the water is on, the bathroom radiator is on, and when we turn the heating on we just turn the pump on which means the rest of the radiators start to heat up too?

Ok so in changing the timer as you describe, basically it means sliding just the hot water on will just do the water, sliding both on will give us both, and sliding just the heating on will also give us both, ie also turn on the hot water and fire the boiler up which it doesn't do at the moment? (Just to make sure ive understood you properly!)

Thanks again and I'll get it swapped over seems easy enough!

 

[ianmcd]

yes basically you have grasped it , I think you may have had a solid fuel boiler at one time if the bathroom radiator heats when on HW only as this is the way they used to be piped to dump the heat when the HW tank was hot enough and nothing to worry about, is worth while setting your programmer the correct way round but if you are happy enough to switch manually when you want the heating on then just do that , wont cause any damage at all, not the most economic system but will work ok

 

[CBF]

that will prob get it to work, however from the OP's details it isn't piped correctly, for gravity h/w to work correctly the pipes from the boiler to the cylinder should be 1" (28mm) but the more worrying thing is that the combined feed & vent is only 15mm & that is not correct at all

 

[ianmcd]

read the whole post OP has a Glow worm space saver MK2 so probably about 25 years old and he doesnt have any problem with his hot water, he has just moved into the house and could not get heating when only CH switched on at programmer but a new programmer recently fitted, dont think he has a pipe sizing problem yes he states that the indirect coil is 22mm but he doesnt really know the difference so without a pic we cant say for sure but if it has run OK all this time I would suspect he has 28mm on the HW circuit

 

[billy1666]

Thanks again for all the help, the wall that the timer is mounted to is getting skimmed in a couple of weeks, so ill flick the switch over when it comes off for that.

Regarding pipe sizes, I think ive got them right, however its had a new cylinder a few years back, at the time they have certainly put a reducer on for the feed from the cold water tank at the point where it attaches to the cylinder, I don't know if they messed with anything else, but the rest of the pipework looks pretty old so probably original.

It may be me getting the sizes wrong though, would it be an issue if it were to be sized wrong? F/e pipe is definitely 15mm, but has worked all this time so far!

 

[ianmcd]

Billy, you dont have anything to worry about, HW is circulating on gravity with your existing pipework so just go with previous information and you will be fine mate