Grant vortex 36e no hot water (or pressure)

[michael8626]

Hi,

I have a Grant Vortex 36e oil combi, over the last few days I have been told the hot water has deteriorated to now which is a very poor flow and luke warm water.

With the heating off the the demand indicator lights up along with the flow switch and DHW pump indicators when the hot tap is turned on.

The hot input to the thermostatic blending valve is red hot, I dont think this is residual heat coming down the pipe from the heat exchanger. But the outlet (mix) pipe on the valve is barely lukewarm?

The boiler is old and it has had heat exchangers before that have scaled up, one only a couple of years ago and I have a scale inhibitor fitted but it is a hard water area.

Should the output on the blending valve be hot when the hot tap is on? Im not sure whether hot water comes from the store to the blending valve and then on to the taps or from the valve and then to the hot water store?

Any thoughts gratefully received.

Thanks

 

[CBW]

Where is this blending valve? Does it supply all outlets or just one? Do you have no hot water anywhere?

 

[oilhead]

Can you adjust the blending valve. It sounds scaled up, and probably will be locked solid. If the input is hot, then the valve is likely to be the problem.
An internet check will be able to find one much cheaper then the official Grant unit.

 

[michael8626]

Where is this blending valve? Does it supply all outlets or just one? Do you have no hot water anywhere?

It sits beneath the plate heat exchanger, No hot water and poor flow rate at all hot taps.

 

[michael8626]

Can you adjust the blending valve. It sounds scaled up, and probably will be locked solid. If the input is hot, then the valve is likely to be the problem.
An internet check will be able to find one much cheaper then the official Grant unit.

Im going back to the property in the morning, I need an angled screwdriver to adjust the blending valve, not enough room to get a stubby in there as I think its the DHW pump in the way directly beneath it.

Its has had a blending valve before and it wasn't the problem, it was the heat exchanger. I cant believe the heat exchanger has scaled up within a year and a half? And I have a scale inhibitor fitted unless its not man enough for the job? It is a hard water area.

That said there has been a leaking basin tap in an upstairs guest bathroom that has left quite a lot of scale deposits so scale or a blockage is likely to be the problem I fear.

Do you think adjusting it could clear it a bit?

 

[CBW]

Scratch that - it's a combi

 

[michael8626]

I am fairly sure the hot pipe to the valve is hot with water and not residual heat travelling back down from the heat exchanger. Also feeling the cold input, it was warm back to the blue water shut off tap, which would suggest a blockage somewhere?

I cant remember that well but when the heat exchanger scaled up before, I thought we had a reasonable flow of water albeit it wasn't hot? I dont think I can remember no hot water and poor flow? If that makes sense.

 

[michael8626]

Can you adjust the blending valve. It sounds scaled up, and probably will be locked solid. If the input is hot, then the valve is likely to be the problem.
An internet check will be able to find one much cheaper then the official Grant unit.

Does the water go from the blending valve to the taps or to the water store please?

 

[oilhead]

Doesn't the blending valve adjust with a knob,(or grips if the knob breaks?) I can't recall seeing one with screwdriver adjustment.

 

[michael8626]

Doesn't the blending valve adjust with a knob,(or grips if the knob breaks?) I can't recall seeing one with screwdriver adjustment.

I think under the white cap is a slotted head for screwdriver adjustment? What you are suggesting makes more sense, I will have a look tomorrow.

Can they scale solid or do you think adjustment make clear it a bit in the short term? This situation seems to have developed very quickly for scaling?

 

[michael8626]

Doesn't the blending valve adjust with a knob,(or grips if the knob breaks?) I can't recall seeing one with screwdriver adjustment.

Hi, yes, managed to adjust with grips.

When I shut the valve I got a good flow of cold water, opened the valve and the flow deteriorated greatly with no hot water.
As I said the hot input to the valve is very hot when a tap is turned on, just concerned it is definitely the blending valve and not the heat exchanger?

 

[oilhead]

Take the blending valve off and try blowing through it. You can also check that there is no obstruction. You may even be able to check the hot water out of the open connection. Just have a bucket ready.

 

[michael8626]

Take the blending valve off and try blowing through it. You can also check that there is no obstruction. You may even be able to check the hot water out of the open connection. Just have a bucket ready.

Many thanks for that. Do I need to drain down for this, where does the water from the outlet (mix) from the blending valve go to? Is it to the store tank or direct to taps?

If it’s the store does it go in top or bottom, hence my question re draining down?

Last question (!) do you know of a link that shows a blown up diagram of the hot water side of things on the 36e?

 

[Terrywookfit]

Water from mixer goes to taps.
Turn cold mains off to isolate and open hot and cold taps.

Water in the store is pumped through the primary of Plate H E.

Cold mains goes through domestic side of P H E to blender.

 

[michael8626]

Water from mixer goes to taps.
Turn cold mains off to isolate and open hot and cold taps.

Water in the store is pumped through the primary of Plate H E.

Cold mains goes through domestic side of P H E to blender.

Thanks Terry

Do I need to drain down the store or will opening taps be sufficient please?