Grant Vortex 21e Hot water but No CH

[markadams]

Got a Grant boiler which recently ran out of oil, manage to bleed oil line, it now fires fine when hot tap is opened but will not fire when in CH mode.

The Demand an CH Pump light are on but not the burner or flow.

It has two Pumps and no Diverter valve, I can't understand why it refuses to light as it works perfect in How Water mode.

 

[SimonG]

Nothing to do with the oil, theres another issue. Does it have a wire free stat or programmer?

 

[markadams]

That was my conclusion about the oil, it has a built in Manual programmer and the room stat is jumpered on permanent.

I have tried it with the Hot water switch to off and CH to constant but no go.

 

[SimonG]

Have you bypassed the timer?

 

[markadams]

No, I assumed that setting the switch to constant would do this.

 

[tamz]

External controls, CH pump or air lock on top side of boiler

 

[markadams]

Hi Tamz,

I suspected the CH Pump, I checked that It has voltage, which it does, I undone the spindle screw and you can hear the spindle turning and water is pumped out of the screw.

It has no external controls, and does not appear air locked.

 

[tamz]

Is it too hot to touch

 

[markadams]

If you mean the pump, it is hot but not too hot to touch.

 

[tamz]

If it is the silver pump the spindle has come off. They are junk. Strip
the head off and check then fit a grundfoss.

 

[markadams]

Yes it is the silver pump, both pumps are Wilo pumps. I have a spare 15-50 pump will that be suitable?

 

[tamz]

Yes. Take the head off the one that is in and you will see the spindle has most likely sheared off the motor.
Had about 4 or 5 of them with grants.
Wilo (euramo in a past life )were never a great pump but they are cheap.

 

[Bunker]

How long have you given it? You know they prioritise the HW first so regardless of controls the heating wont come on until the HW store stat is satisfied. If it has been running a while then the store stat could be knackered and not letting it click over.

Ah...hang on, you said the CH pump is running...so yes, as above, probably dud.

 

[markadams]

A merchant told me that the 15-50 pump is not suitable for these boilers. Don't know why.

 

[markadams]

Bunker, Certainly been left long enough. All points to the pump, I suspected the pump but wanted it confirmed as I thought I was going to have to get a new one but if the 15-50 is suitable then I can try that.

Mark.

 

[tamz]

Cos he is a merchant.

 

[tamz]

It is a 6m head pump that comes fitted.
Think of it this way. Do you need a 2 litre car to drive on the motorway. A one litre car will still do 70mph.
Pumps are sized and adjusted to suit the system. A 15 50 will do 95% of domestic systems no problem especially on a lump of cast iron.

 

[markadams]

Thanks all for the help.

I will report back when I have changed it

 

[Best]

The 6m pumps are supposed to be for the extra resistance in a condensing boiler (I always heard) and also in modern fancy radiators with restrictive waterways - like a lot of column rads. Or on long pipe runs or 8mm & 10mm microbore systems. Can make a massive difference on some systems especially larger houses & shows up in bad winter weather if your pump ain't getting the heat up to temperature in some of the rads.

 

[markadams]

The whole house is piped in 8mm pipe, horrible stuff. Given this maybe a 6 meter pump would be better.

 

[markadams]

Hi,

Well I swapped the pump and the boiler fired up in CH mode and ran for about 10 minutes then the demand light went out and it stopped.

It has no room stat (just a jumper wire) and it is in constant so programmer is by-passed. I switched off the power and back on then the demand light lit again, after about a minute it fired again and did the same thing.

I thought it was the programmer/room stat that controlled the Demand light, is that correct?

Mark.

 

[SimonG]

Air locked in central heating. Is the pressure gauge goosed and theres not a lot of water in?

 

[markadams]

Air locked in central heating. Is the pressure gauge goosed and theres not a lot of water in?

Pressure gauge works perfect, the CH works perfect for ten minutes then switches off so would have thought it unlikely that it has an air lock? This would also not explain why the Demand light goes out?

Mark.

 

[MarkOil]

Could be the board, seems a bit odd.
If the demand light is now going out, do you have power from the programmer to the boiler?
I'd be looking at your programmer

 

[Bunker]

Could be the board, seems a bit odd.
If the demand light is now going out, do you have power from the programmer to the boiler?
I'd be looking at your programmer

Get your voltmeter out and call Grant, they will talk you through some tests