Myson Apollo pump running all the time

[Notebook]

Myson apollo
long story but here goes
direction - zone -valve above pump was not switching corectly - rads getting warm.
Changed the valve, but water got on the terminal block (under the valve!!!) and the pump and there was a smell of burning windings / tripping electric when switched on. changed pump. electric ok.
This was a while back - a few months. Only using hot water.

Cold weather arrived
Turned on heating and selected high button - all ok
However if I turn on Low button then the rads warm p etc as with high but noticed the pump running all the tiime. Checked wiring with my neighbours and all looks the same.
Someone suggested change overrun stat on boiler incase that was it. No difference.
On high heat all works fine.
On low heat on boiler, the pump runs all the time.
On high and low, room stat works fine and room temp is controlled ok.
with the cold weather I have had it on high heat, but now want the boiler on low.
just went to the cylinder stat and it is set on 60.
If i turn this down the (stat on low) pump stops (say 50) and if I turn it up to 65 the pump kicks back in.
Hope this helps
Also pic of isolation vaves around pump etc.
Should all these be turned on? they are, but possibly I altered them when working on the system.

Nick

 

[HTB]

I had some very similar problems on my Apollo, was on going for long time, in the end got fed up and I changed controller, 3 way valve and stats. All Fine now.

In retrospect I might have gone for disposing of 3 way valve and modified y/plan to s/plan and fitted 2 simple zone valves which I think would have been better as I subsequently installed a Hepworth underfloor expansion pack in my conservatory and zoning for more eficient control of this would then have been easier.

BTW looks like you might have opened your balance valve all the way and you might want to tweak that back in a bit. It's the highest one on your picture,,,on 15mm tube with no wheel head on it. Don't close it all the way, count the number of full turns from closed to open and try setting it on half see if that helps. Consider replacing it it auto by pass valve.

 

[Notebook]

I had some very similar problems on my Apollo, was on going for long time, in the end got fed up and I changed controller, 3 way valve and stats. All Fine now.

In retrospect I might have gone for disposing of 3 way valve and modified y/plan to s/plan and fitted 2 simple zone valves which I think would have been better as I subsequently installed a Hepworth underfloor expansion pack in my conservatory and zoning for more eficient control of this would then have been easier.

BTW looks like you might have opened your balance valve all the way and you might want to tweak that back in a bit. It's the highest one on your picture,,,on 15mm tube with no wheel head on it. Don't close it all the way, count the number of full turns from closed to open and try setting it on half see if that helps. Consider replacing it it auto by pass valve.

Hi
Thanks for your reply - A few questions.
The balance valve - what does that do? How does it work? Looks like with this open, the water can just circulate into the tank?
Will open it half way and give it a try - what then? what happens if I go a turn more open / closed etc?

Stats
Is there a low and a high stat on the side of the boiler? If so might be worth me changing the low?

Really appreciate all your help - nice to have an answer rather than someone teling you to google etc.
Again thanks
Nick

 

[doitmyself]

On low heat on boiler, the pump runs all the time.

Is it just the pump which runs all the time or is the boiler also staying alight all the time?

Just went to the cylinder stat and it is set on 60.
If i turn this down the (stat on low) pump stops (say 50) and if I turn it up to 65 the pump kicks back in.

If you have a mid-position valve, the boiler is either controlled by the cylinder thermostat or the valve. If heating is OFF and hot water ON, the boiler is controlled by the cylinder stat. If both heating and hot water are on,the boiler is still controlled by the cylinder thermostat. If the HW goes off (at HW thermostat or the timer) the boiler is now controlled by the valve.

Therefore, as the pump stopped when you turned the cylinder stat down the system must have been in either HW only or HW & CH. You say you want to run the boiler switch to Low. The problem with this is that it the water temperature leaving the boiler is only about 65C. This is fine if you are just heating the HW cylinder, but not really enough for central heating. I assume you have a room thermostat. If you do there is no benefit in having the boiler stat on low when heating is on.

Also pic of isolation vaves around pump etc.
Should all these be turned on?

The valves immediately either side of the pump must, obviously, be full on.
The one without a handle, on the T above the pump is a bypass valve. It allows some of the hot water to be fed back into the return to the boiler. This should be about one turn open.

The other two valves are isolation valves for CH and HW circuits. The CH one can be fully open but the HW should be about half open - if it is open too much the cylinder will takie more than its fair share of the flow when both CH and HW are ON.

 

[Plouasne]

Cab I offer just one word of advice, never ever, open any valve full on, always back it off at least half a turn, if not a full turn, this way you can possibly open the valve a bit more, to loosen any muck that is stopping it from closing, then close the valve

 

[doitmyself]

Cab I offer just one word of advice, never ever, open any valve full on, always back it off at least half a turn, if not a full turn, this way you can possibly open the valve a bit more, to loosen any muck that is stopping it from closing, then close the valve

Excellent advice. I always do this myself.

 

[Notebook]

A. only the pump runs all the time - the boiler kicks in and out as normal. On high it appears to work fine.

B. It was on HW and CH
I have used it on low for years - on high its a bit noisy as its a small house and in the kitchen off the living room, but I see what you mean as it indeed has a room stat, so noise really, but as that valve was fully open I will try it tonight with it partially closed.


C.
The CH one can be fully open but the HW should be about half open - if it is open too much the cylinder will takie more than its fair share of the flow when both CH and HW are ON - have changed the phot so that it is easier to say which is which.
Therefore, which is the ch and which is the hw.
Again thanks all

 

[doitmyself]

Only the pump runs all the time - the boiler kicks in and out as normal. On high it appears to work fine.

Very Odd! The only thing that can keep the pump going is the overrun thermostat. This will happen until the water temperature has dropped to a preset temperature. There can only be two causes for the pump running continuously: a faulty oveheat thermostat or a mis-wired pump. Can you say how the pump has been wired?

Therefore, which is the ch and which is the hw?l

A = HW - half open
B = CH - full open then close half a turn
C = Bypass - one turn open
D = Pump valve - full open then close half a turn
E = Pump valve - full open then close half a turn

 

[Notebook]

Hi
Forgot to say, changed the overun stat - guess I wired it correctly?

The pump wireing - its in the terminal box - can you work it out from wire colours if I supplied them?
However it all works ok on high?

I will adjust the valves as you said and turn it on for an hour with the room stat just high enough for it to kick in.

Again thanks

 

[doitmyself]

Forgot to say, changed the overun stat - guess I wired it correctly?

If you had wired it wrongly, I think you would have the fault on both High and Low.

Which model Apollo do you have? It's on the inside of the front cover together with the GC number.

The pump wireing - its in the terminal box - can you work it out from wire colours if I supplied them?

Wire colours mean nothing as installers have their own way of wiring and do thing such as using the earth and neutral wires as live feeds - saves buying a cable with different coloured wires. The only colour which seems to be sacrosanct is brown.

Although the pump is connected to the terminal box, there should be a wire from there to the pump terminal on the boiler. Can you take a pic of the terminal box (lid off!!) and say what each cable connects to?

 

[Notebook]

Hi
apollo 15/30, 30/50, 40 and 50/65?
also 8706 on a rivet

pump brown is connected to a red dissapearing into the wall
blue to blue on 3 way valve
earth to earth
ashes to ashes

getting back to stats - what about the lo stat?

 

[doitmyself]

apollo 15/30, 30/50, 40 and 50/65?

What's the GC Number - starts with 41

also 8706 on a rivet

Guess that's date - June 1987

pump brown is connected to a red dissapearing into the wall
blue to blue on 3 way valve
earth to earth
ashes to ashes

That's OK. The other end of the red should connect to the terminal marked pump live at the boiler

what about the lo stat?

Can't see how that can have anything to do with the problem. The fact that the boiler goes out shows that the low stat is doing its job. Pump running is controlled by the overheat stat.

The overheat terminals should be wired: 1= red, 2 = Yellow, 3 = Brown

When the water is cold, terminals 1 and 3 are closed. When the water is hot, terminals 1 and 2 are closed.

 

[Notebook]

467423 is the only other number on there - on same rivet - different tag.
Silly me - of course it must be working - stat
will check the overheat

overrun wired correctly - checked sticker with theone I originally had on there and the number is the same

 

[doitmyself]

467423 is the only other number on there - on same rivet - different tag.

That sounds like a part number. There should be a metal plate fixed to the back of the boiler front cover with all the boiler data on it. The GC number will be on this plate.

overrun wired correctly - checked sticker with the one I originally had on there and the number is the same

What is the number?

Have you checked continuity of the OH stat, as in my previous email?

Just a thought. The Low/Off/High Switch may be faulty.

If you can understand wiring diagrams, you will find the Apollo info at [DLMURL="http://www.partsarena.com/baxi/"]PartsArena[/DLMURL]. When you first use the site it will ask to install a small app to read the files.

 

[Notebook]

4178953
15/30B - 37500

checked stat in cup of boiling water and acting correctly

why low / high off switch faulty?

will look at drawings

again thanks

any ideas which mine is?

 

[doitmyself]

4178953
15/30B - 37500

That's a Thorn Boiler! The same boilers were sold under Thorn and Myson badges. 15/30B is the model number 15,000-30,000BTU Output.Don't know what 37500 means apart from the fact that it is the input at max output.

You can find the boiler manual on PartsArena listed under Myson/Boiler/Apollo/30B. It has a different GC number because it had the Myson badge on the front!

checked stat in cup of boiling water and acting correctly

Good

why low / high off switch faulty?

Just thinking out loud.

Some more thoughts:

1. You say the motorized valve was replaced. Are you sure you replaced it with the correct valve? What is the make/model no of the valve?

2. You say the junction box got fried when you replace the valve. Did you replace the box and did you check all the wiring?

3. You have a built-in timer which will only provide HW or HW and CH. There is no CH only. So how did you wire up the new valve?

 

[Notebook]

1 - siemens 3 port CMV3 A goes to central heating B goes to cylinder
on diagram my override? lever is on the other side - will the head mount the wrong way?

2 - check wiring - how?


will look at how I wired it now

ok
valve
blue - blue pump
grey - black on stat
white - black (into wall)

the orange(switchable live?) is connected to blue from stat on tank and a red going into the wall

This I take it the red goes to the over run stat on the boiler?

There is another red in the terminal block - wonder if I had mixed them up?

the only other red I can see on the drawing is marked HW

 

[doitmyself]

1 - siemens 3 port CMV3

CMV3?? (Should be more numbers)

A goes to central heating B goes to cylinder
on diagram my override? lever is on the other side - will the head mount the wrong way?

It's connected the correct way round.

check wiring - how?

I am thinking of physical damage, e.g burnt insulation, wires shorting together. loose strands touching another terminal etc.

valve
blue - blue pump Neutral
grey - black on stat cylinder stat? Which terminal?
white - black (into wall) should go to room stat

the orange(switchable live?) is connected to blue from stat on tank and a red going into the wall

The blue should go to call on the tank stat

This I take it the red goes to the over run stat on the boiler?

NO. This wire is the switched live to the boiler

There is another red in the terminal block - wonder if I had mixed them up?

Possibly. Didn't you write anything down when you disconnected the wires!

Is there anything else connected to this other red terminal?

the only other red I can see on the drawing is marked HW

What drawing? Can you post a copy?

 

[Notebook]

Leaflet
CZV222
and
CMV3.. so I guess cmv322 = 22mm?

grey to cylider stat will remove to find out

"The blue should go to call on the tank stat" - what about the red with it?

switched live to the boiler - same thing looking at the "drawing"?

red - will look block - wife in shower etc

drawing is the one on the site you said - right at the end


Looking at the valve leaflrt there is a section for wiring - with or without over run....
not clear what the leaflet is saying - very small print - will try to get a copy

again thanks for your help

http://www.buildingtechnologies.sie...nts/sbt_internet_uk/residential/cmv_czv_d.pdf

 

[doitmyself]

Forget what I said. You have a Myson timer, so the wiring is non standard. Here is a wiring diagram from the Apollo wiring book showing how you wire up a mid position valve; it's different, to say the least. The main changes are on the hot water side. This is because the timer will only allow CH with HW.

The HW stat Common terminal goes to HW terminal on the boiler (3 from top).
The HW stat Call terminal goes, with valve orange, to the ON terminal of the boiler (6 from top)
The HW stat Sat terminal goes to valve grey.
Room Stat Live to CH ON terminal on boiler (4 from top)
Room Stat Switched live to Valve white
Room Stat Neutral to any local neutral
Pump Live to Boiler Pump Live (8 from top)
Pump Neutral and earth to local N and E terminals

 

[Notebook]

Hi
Bit tied up for a day or two - might be worth noting down wiring as it is and then starting again. Is there any way of checking where wires go when they enter the wall behing the junction box, or just by removing the room stat downstairs etc to see what wires are what.
The terminal box in the original pic has 8 connectors, dont know if that makes any difference.
Again thanks for your help

 

[doitmyself]

might be worth noting down wiring as it is and then starting again.

Excellent idea.

Is there any way of checking where wires go when they enter the wall behind the junction box, or just by removing the room stat downstairs etc to see what wires are what.

How many cables go into the wall and where do you think they go?

Don't forget all the wires in a cable must go to the same place. So you only have to identify one wire in a cable and the others are obvious.

Non standard colors are a great help (i.e not brown, blue or green/yellow)

If you have a multimeter you can use that to identify cables - with the power off. For example, turn the room stat to max. Find what you think is the other end of the cable to the room stat and disconnect it. Set the meter to Ohms or Continuity and connect the two wires to the meter leads (either way round); Depending on the meter it will either beep or show a very low reading. If this happens, you have correctly identified the cable. You can confirm by setting the room stat to min, the meter should stop beeping or go to open circuit. If no result, try another cable with the same colours. In some cases you will have to disconnect the wires at one end and temporarily twist them to gether to make a circuit.

The terminal box in the original pic has 8 connectors, dont know if that makes any difference.

I take it you are talking about the terminal box on the wall. If it is just a strip of 8 connectors, it can be used. This is the the "junction box" in the Apollo wiring diagram.

The diagram shows the pump connected directly to the boiler. As your pump is remote you will have to connect it via the Junction box. Connect pump Live to a spare terminal and run a wire from that terminal to the boiler pump live terminal.

The diagram shows the neutral connection coming from the boiler. Is that what happens in your case or does the neutral come from somewhere else?

I assume the Main power connection is direct to the boiler,as in the diagram.