testing a 'Boiler mate' thermal store thing

[bster]

If i record the temp of the CH flow from the Boiler mate and it is 77 degrees (as required by the MI's) does this mean that the whole cylinder is heated to the same temp? - if so what temp should the DHW out be (before the blending valve)?


if taking the CH flow temp is not the recommended way to test the store temperature then what is?

 

[corgiman]

Sorry mate I dont have a clue

what do the lads at gledhill say?

 

[bster]

I dont get the 'pleasure' of talking (or waiting) to tech help, they havent given me a works phone yet!

 

[pannierstan]

If the store is at 77 then thats pretty good. And yes the whole store should be near that depending on the stratification.

Depending on the model of Gledhill you mean as there are many then the outlet from the DHW primary should be very close to that and then obviously mixed at the blending valve to maintain 55-60 ish

Why whats up?

 

[bster]

the DHW is crap, replaced blending valve (no difference) digi thermometer showed that primary circulators were only 60 degrees, so isolated prob back to Potterton netaheat (it was switching off at 60 degrees) replaced boiler stat, apparently same problem(its not my job), dont know iof other engineer tested flow temp from boiler after stat replacement though.

 

[pannierstan]

Hmmm, well that will be the first thing to check, but after that you might guess that if the store is definatly 80 deg and the water coming out isnt it means the DHW coil inside the Gledhill is not getting heat from the water (sound familiar)
Dont forget that those gledhills work like a back to front cylinder so the large mass is central heating water and the water in the coil is DHW to the taps.
A model would be most useful as some have twin pumps on the jig and a calorifier on the side. Then things really get interesting!

Check condition of system water.

Stan

 

[bster]

I understand how thermal stores work And the reason for my post is that if its proved that the store is at 77 degrees and the DHW outlet is only XXdegrees that it would confirm a scaled DHW HE (BTW- what type of HE do they entertain?). Its an older model apparently, it has two pumps and is a vented store.

What sort of temp drop on the DHW is expected from the store temp, if we have got 80degrees would the DHW be 60degrees?

 

[Softus]

The boilermate DHW coil is notorious for scaling, and descaling won't take as long as you're spending wondering about what to do about it.

 

[Biggles..]

Have you tried the onboard diagnostics of the gledhil,l that will tell you all your temps and the serviceability of your sensors. Have had a few on a wimpy estate(only builder round here to fit them) where the hot water sensors have failed causing poor and fluctuating hot water temp.

 

[bster]

There is no on board diagonosis system!

I cant go ahead and descale, I'm the apprentice remember

 

[cross thread]

just had a similar prob ,turned out to be a faulty mixer tap adding cold to h/w circuit

 

[bster]

mixer valve has been changed, the store isnt heating up correctly because the primary flow from boiler is switching off at 60 degrees, but i would like to know the temp drop from 77degrees ( Gledhills stated store temp) to the temp expected at the DHW before the blending valve.

 

[cross thread]

i would expect the outlet temp to be just below stored water temp.what about the stat on the store have you checked that,the one i worked on was adjustable

 

[Biggles..]

Its not the boilermate 2000 then if no onboard pcb and diagnositcs.Plate heat exchangers for some of these are made by a company called swep but cant think what its made of.Is it a twin pump, with one circulating the primaries through the plate heat exchanger.did you try altering the speed of this pump. If you did and no difference its looking like the HE is scaled up.

 

[bster]

defo a twin pump, one for primary and other for CH.

At the mo the stat on boiler has been replaced (as it was not getting up to 85 degrees on the flow) but I dont know if that has fixed prob as the person who fitted it didnt have his thermometer (broken) but reackons that DHW is still below temp, though he may have not waited long enough for the store to recover from the 60degrees backl up to the required 77.

I'm basically fishing for info as I doubt I'll be going back to the job. so thanks again for all your input people.