Vaillant ecoTec boiler S.7 pump over run

[daveofbristol]

Hi there
My boiler seems to permanently display a status code of S.7 "Pump Over Run". Is this telling me there is a problem somewhere?
(We have just changed various settings and I'm not sure if there is a problem or not).
The boiler displayed temperature never seems to reach the targets set for both water or heating flows.

Thanks
Dave

 

[David937]

What various settings have you changed and why?

 

[daveofbristol]

Just lowering temp settings on boiler and timer settings - nothing serious.

 

[ALEC1]

which vaillant is this?

 

[daveofbristol]

ecoTec 624

 

[ALEC1]

and what controller?

 

[daveofbristol]

Its an ecoTec Plus 624 boiler (to be more accurate).
The heating is controlled by a Danfoss TP5000 controller in the hall.
The water system has a storage tank. When the Vaillant was installed the guys left the old controller in place, with instructions to leave the water on 24 hours a day.
All I've done recently is lower the boiler settings to their summer positions, about 48 degrees for both water and heat.
Most of the time, and especially after a shower, the display shows 40 degrees or less, and the water is cold.
Do you know why the display only shows a single (presumably heating) temperature, when, as I understand it, it is maintaining 2 different circuits?
According to Br Gas we are consuming 80% more gas than we should be for our size of house, so I wanted to reduce the boiler temp, with the result that we seem to have cold water most of the time.
If the target is 48 degrees and the tempereature is only 40 surely the boiler should be coming on? The "i" button seems to be mostly on S.7 as I mentioned.
Thanks ever so much

 

[Agile]

The boiler needs to be set while heating water to give about 10 C higher than the target temperature you set on your cylinder.

Cyls are usually set to 50-60 C.

One of my Chinese customers sets her cyl to just 44 c and uses the water direct without adding any cold! I wonder if its any coincidence that she is an accountant?

Tony

 

[daveofbristol]

OK, so I'll increase the water temp to 55 as you suggest, thanks.

I'm confused about what controls the tank temperature (and how I can see what temp is at).

The guy who put it in said that he didn't replace the tank thermostat, but I assumed it would only be used if the emersion was on.

Does the Vaillant rely on the tank thermostat working correctly, then?

Would that be an easy thing to replace, without replacing the tank itself?

Thanks again

 

[David937]

OK, so I'll increase the water temp to 55 as you suggest, thanks.

I'm confused about what controls the tank temperature (and how I can see what temp is at).

The guy who put it in said that he didn't replace the tank thermostat, but I assumed it would only be used if the emersion was on.

Does the Vaillant rely on the tank thermostat working correctly, then?

Would that be an easy thing to replace, without replacing the tank itself?

Thanks again

The thermostat which controls the temperature of the hot water coming out you taps is usually on the hot water cylinder. It will look similar to this:

On the Vaillant boiler, the control knob for the hot water has no effect unless you have Vaillant controls (which you don't) so that can be ignored. So your cylinder stat should be set at about 55ºc and the boiler set at, at least 65ºc to heat the cylinder sufficiently.

 

[Agile]

Although my customer uses her water at 44 C its not recommended because it can allow the legionella to multiply.

The minimum recommended cyl setting is 50 C

Tony

 

[David937]

Although my customer uses her water at 44 C its not recommended because it can allow the legionella to multiply.

The minimum recommended cyl setting is 50 C

Tony

I hope you told her to increase the temperature!

 

[gaswizzard]

The minimum recommended cyl setting is 50 C

Tony

Suggest you stay off that french wine , been a few BS posts of late Tony.

 

[Mamps]

Hi there
My boiler seems to permanently display a status code of S.7 "Pump Over Run". Is this telling me there is a problem somewhere?
(We have just changed various settings and I'm not sure if there is a problem or not).
The boiler displayed temperature never seems to reach the targets set for both water or heating flows.

Thanks
Dave

Dave - did you manage to get this fixed? I have exactly the same problem. house won't get past 16 degrees and i've set it to 22.
Rads are warm, not hot. Boiler is showing s7 or s8 error codes
Any advise would be greatful, thanks.
Mamps

 

[daveofbristol]

Turned out with mine that it had been wired incorrectly, which explains a lot.
It's re-wired today in fact, so hopefully the bills will come down!