Grant vortex pro external 36e poor hot water

[Nathan Smith]

Check the diverter valve, diverter valve diaphragm if fitted on that model.
Also found this on Grant manual

Store switch - Allows the primary store to be manually switched off if hot water is not required. With the switch set to OFF, the burner will not fire to maintain the water temperature in the store and the hot water (store) pump will not operate.
IMPORTANT: The boiler will not produce hot water.

This model doesn’t have a diverter valve. It’s all done with two separate pumps. Almost wish it did as that would more than likely be the case.

Also no on/timed/off switches on this one it’s all controlled externally. Hot water is on demand wired up permanently and heating is controlled by a nest went over all the wiring and checked with the electrician when he popped in one day while I was there.

 

[Millsy 82]

If the pump is coming on, its a new pump and the plate isn't getting hot it says to me 1 of two things blockage or air.

Is there a non return valve on the pump or is that just on heating pump. I would whip the plate out the pump out etc and make sure there is no blockages.

Also what pump have you put in? A wilo? I've had a new one that spun but the spindle was broken so the impeller didn't spin. So maybe try switching the heating and hotwater pumps over.

 

[Nathan Smith]

If the pump is coming on, its a new pump and the plate isn't getting hot it says to me 1 of two things blockage or air.

Is there a non return valve on the pump or is that just on heating pump. I would whip the plate out the pump out etc and make sure there is no blockages.

Also what pump have you put in? A wilo? I've had a new one that spun but the spindle was broken so the impeller didn't spin. So maybe try switching the heating and hotwater pumps over.

Not had a new pump, but have swapped the CH and DHW pumps over to test any fault. Brand new plate exchanger so unless it blocked after it was swapped? Return manifold has been removed and is all clear.

Yes there is a non return valve below the pump before the water enters the store. Only part I’ve not got involved with.

Have cracked all the nuts while it’s all been running to see if it’s air trapped but all let water out with no air.

 

[Gazzt]

Did you trace the fault

 

[Nathan Smith]

Did you trace the fault

No still no joy. Trying to find time amongst a busy schedule to spend on it is proving difficult, that and my supplier messing up my order for a non return valve.

Ordered one that will be here Thursday so going down to fit that and see if it’s that at fault. Theory being if it’s not opening fully it’s not allowing the flow through the heat exchanger quick enough to cope with the demand but withe no hot water being drawn off it cycles enough to satisfy the store.

 

[John.g]

Any update on a fix for the above?.

 

[Nathan Smith]

Any update on a fix for the above?.

Yes been meaning to post back in here.

Turned out to be the non return valve on the DHW pump. All though it moved, my guess was that due to the magnetite build up on it when it got hot it stuck and didn’t open fully. Put a new one on and it’s all working fine.

 

[WHPES]

Following. Any progress? I had this problem and found the water jacket was full of sludge. I cracked open all the plugs, disconnected the pipework and dangled a drain jetting hose inside. You wouldnt believe the sludge that came out

 

[Nathan Smith]

Following. Any progress? I had this problem and found the water jacket was full of sludge. I cracked open all the plugs, disconnected the pipework and dangled a drain jetting hose inside. You wouldnt believe the sludge that came out

Yes it was the non return valve on the bottom of the DHW pump. Was sticking when it got hot so put a new one on and problem solved