Hot Water Not Getting Hot baxi 105e.. The Return!!

[neilyp]

Boiler is a Baxi 105e 2 years Old / System was not flushed originally although it was a combi before this one.

My area is not a hard water area

Fault : hot water not heating up {Will get hot if tap runs real slow}

Original Suggestions : Scaled Up Hot Water HE / Loss of Heat Transfer

However this is right at the back of the Boiler and is going to Involve lots of work to get at it.
Im currently at a training centre doing my Gas certs etc.. And its been put to me that a scaled up HE would also decrease the water flow (which doesn't appear affected)

I have checked the 3 port valve incase this was not closing completely when Hot water was called for and still sending water to the flow. However this is fine.

Has anyone got any other suggestions or am i really going to have to dismantle the boiler.

 

[fitz1]

takes about 5 min to get the dhw heatx out.isolate boiler, drain from white drain valve on right of pump ,undo 2 philips screws holding heatx using long reach screwdriver, lift out over top of diverter. or take pump out and lift it out that way. make sure you protect control panel from water spillage.

 

[Nixt]

The problem is not scale on the dhw side but debris on the primary side of the plate, hence poor heat transfer. Flow pipe to plate inlet will get very hot, return too cool and dhw only hot with minimal flow. Even if flushed takes only minor flakes to block, when you cut one open you'll see how easy.

 

[neilyp]

Excellent, I will take another look, most of the boilers ive looked at have the HE at the front so when i saw this right at the back it looked pretty daunting.... it also makes more sense that the CH side of the DHW is blocked with debris as i have done a lot more work on rads etc.. than the cold supply.

I will take all this onboard and challenge the problem again this week!

Thanks again i will come back with an answer!

 

[baxpoti]

I think the quickest and easiest way to get the plate H/E out is to remove the gas valve.

 

[HarrogateGas]

Rather than beating around the bush why dont you get hold a touch thermometer and measure the temperatures to see what the heat transfer is like and prove once and for all?

 

[neilyp]

I have fitted a Brand new DHW (It took less than 5mins and came out without moving anything) however its still not sorted the problem.

I have checked the flow rate on the HOT tap with a weir gauge / cup and its running at 8litres per minute which is fine as The boiler will do just over 11.

My next suggestion is that maybe the diverter valve on it is not moving over completely when hot water is called for and sending some water to the CH circuit. Therefore not getting enough water to transfer sufficient heat via the DHW excahnger.

I have ran the hot tap and held the flow pipe which is not warm but not too cold either. (This is going to cost me a few quid so i need to be certain there is no more other avenues)
Any ideas folks please.

 

[nickso]

whats the tap water temp at 8 litres a minute?

have you checked the burner pressures?

the flow pipe getting a little hot can be the the heat transfer through the boiler/pipe. how quickly does it get hot?

 

[neilyp]

the flow pipe doesnt actually get hot just not uncomfertable to touch. I to thought it could just be heat conducting through the pipe work.

Not sure what the temp of the incoming cold water is but too be honest, my friend has exactly the same boiler fitted only a few days after mine and lives only a few doors away yet he has not had this problem so i cant see a drop in incoming water temp to be a problem.

 

[nickso]

sorry i wasnt very clear.

whats the hot water temp from the tap at 8 litres a minute?

have you checked the burner pressures?

 

[neilyp]

temp is about 30 degrees, by the time the bath was full its cold.
Central heating can go right up the scale so if the pressure is fine for this then i couldnt see it being different for the Hot water? Is this right or not?
cheers

 

[gas4you]

temp is about 30 degrees, by the time the bath was full its cold.
Central heating can go right up the scale so if the pressure is fine for this then i couldnt see it being different for the Hot water? Is this right or not?
cheers

Does the heating flow pipe get hot when the hot taps are turned on? if so points to diverter valve.

 

[neilyp]

not really, this is what i thought but to be honest the flow pipe dont get hot just sort of room temp. Its going to cost be £100 quid for a new valve so i want to check all other possibilities first.

 

[gas4you]

Have you checked DHW diaphragm? Remove microswitch housing on the front of diaphragm assembly, does pin pop out ok when hot taps on?

 

[neilyp]

Have you checked DHW diaphragm? Remove microswitch housing on the front of diaphragm assembly, does pin pop out ok when hot taps on?

Are they straight forward to dismantle? I wasnt sure as it looks very different to the type found on Y plans and other combis.

i understand how a diverter works but not the exact technical workings, could you explain a bit more so i no what it is your suggesting and then i will check?
Also can any of the bits in it be replaced?
Cheers