My Vaillant Ecotec Plus 637 boiler wouldn't start this morning - error
message saying something like "Water shortage at pump", though the
pressure reading was OK.

--
Algernon

On 13/12/2022 11:10, Algernon Goss-Custard wrote:
> My Vaillant Ecotec Plus 637 boiler wouldn't start this morning - error
> message saying something like "Water shortage at pump", though the
> pressure reading was OK.
>

I would try warming the controller with a hair drier, electrolytic caps
that are on the way out are seriously derated in the cold

--
Global sea level rise to 2100 from curve-fitted existing altimetry data
<http://diverse.4mg.com/slr.htm>

On 13/12/2022 11:10, Algernon Goss-Custard wrote:
> My Vaillant Ecotec Plus 637 boiler wouldn't start this morning - error
> message saying something like "Water shortage at pump", though the
> pressure reading was OK.

Did you get a fault code (typically F<digits>)?

Can you hear the pump spin up?

It could be the pump not working, or it could be the pressure sensor
that is used to detect the abrupt change in pressure when the pump
starts is not seeing what it is expecting. (could be pump, or sensor
related).

You can take the big silver cap off the front of the pump (have a cloth
handy it will weep a bit of water) and check the impeller spins freely
when turned with a screwdriver (of pozi/phil typically).

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

On Tuesday, 13 December 2022 at 17:23:07 UTC, John Rumm wrote:
> On 13/12/2022 11:10, Algernon Goss-Custard wrote:
> > My Vaillant Ecotec Plus 637 boiler wouldn't start this morning - error
> > message saying something like "Water shortage at pump", though the
> > pressure reading was OK.
> Did you get a fault code (typically F<digits>)?
>
> Can you hear the pump spin up?
>
> It could be the pump not working, or it could be the pressure sensor
> that is used to detect the abrupt change in pressure when the pump
> starts is not seeing what it is expecting. (could be pump, or sensor
> related).
>
> You can take the big silver cap off the front of the pump (have a cloth
> handy it will weep a bit of water) and check the impeller spins freely
> when turned with a screwdriver (of pozi/phil typically).
>
>
>
> --
> Cheers,
>
> John.
>
> /=================================================================\
> | Internode Ltd - http://www.internode.co.uk |
> |-----------------------------------------------------------------|
> | John Rumm - john(at)internode(dot)co(dot)uk |
> \=================================================================/
I've had pumps shear the impellor shaft on odd occasions. The rotor spins but the impellor doesn't.

John Rumm <see.my.signature@nowhere.null> posted
>On 13/12/2022 11:10, Algernon Goss-Custard wrote:
>> My Vaillant Ecotec Plus 637 boiler wouldn't start this morning -
>>error message saying something like "Water shortage at pump", though
>>the pressure reading was OK.
>
>Did you get a fault code (typically F<digits>)?

Yes, I'm pretty sure it was F.74 (Pump/ water shortage). The manual
advises me to check the water pressure sensor, pump, heating circuit and
bypass. It suggests running the purge check programme.
>
>Can you hear the pump spin up?
>
>It could be the pump not working, or it could be the pressure sensor
>that is used to detect the abrupt change in pressure when the pump
>starts is not seeing what it is expecting. (could be pump, or sensor
>related).

It did work this morning, though.

>You can take the big silver cap off the front of the pump (have a cloth
>handy it will weep a bit of water) and check the impeller spins freely
>when turned with a screwdriver (of pozi/phil typically).

That old one! Used to do that on a CH pump thirty years ago, every
autumn.

I'll have to work out how to remove the boiler front cover. And wriggle
my ageing back into the back of the cupboard.

--
Algernon

On 14/12/2022 08:32, Algernon Goss-Custard wrote:
> John Rumm <see.my.signature@nowhere.null> posted
>> On 13/12/2022 11:10, Algernon Goss-Custard wrote:
>>> My Vaillant Ecotec Plus 637 boiler wouldn't start this morning -
>>> error  message saying something like "Water shortage at pump", though
>>> the  pressure reading was OK.
>>
>> Did you get a fault code (typically F<digits>)?
>
> Yes, I'm pretty sure it was F.74 (Pump/ water shortage).  The manual
> advises me to check the water pressure sensor, pump, heating circuit and
> bypass. It suggests running the purge check programme.
>>
>> Can you hear the pump spin up?
>>
>> It could be the pump not working, or it could be the pressure sensor
>> that is used to detect the abrupt change in pressure when the pump
>> starts is not seeing what it is expecting. (could be pump, or sensor
>> related).
>
> It did work this morning, though.
>
>> You can take the big silver cap off the front of the pump (have a
>> cloth handy it will weep a bit of water) and check the impeller spins
>> freely when turned with a screwdriver (of pozi/phil typically).
>
> That old one! Used to do that on a CH pump thirty years ago, every autumn.
>
> I'll have to work out how to remove the boiler front cover. And wriggle
> my ageing back into the back of the cupboard.

If it is like mine, there is a single screw on the underside, in the
middle, that pinches on a slot in the front panel (so you only need
loosen it rather than remove it. There are also two metal clips on the
bottom of the front panel either side of the screw. You push these up
with your thumb to disengage them. The bottom then swings out, and you
can lift the cover off the hooks at the top.

(to refit you may need to push them up a bit as you push the bottom of
the front panel toward the boiler - it should click on the clip each side)

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

John Rumm <see.my.signature@nowhere.null> posted
>On 14/12/2022 08:32, Algernon Goss-Custard wrote:
>> I'll have to work out how to remove the boiler front cover. And
>>wriggle my ageing back into the back of the cupboard.
>
>If it is like mine, there is a single screw on the underside, in the
>middle, that pinches on a slot in the front panel (so you only need
>loosen it rather than remove it. There are also two metal clips on the
>bottom of the front panel either side of the screw. You push these up
>with your thumb to disengage them. The bottom then swings out, and you
>can lift the cover off the hooks at the top.
>
>(to refit you may need to push them up a bit as you push the bottom of
>the front panel toward the boiler - it should click on the clip each
>side)

Yes, much the same. It is more that the thing is stuck in the corner
behind some airing shelves.

I did a purge cycle. Not sure whether it did any good, there seems to be
no way you can test for air in the system, but at least the boiler is
running. And it's much milder today. I haven't bled the pump yet. It is
running, and the relevant diagnostic says it is going at 100%, but one
can't tell whether it really is running at full speed.

--
Algernon