My hot water seems far too hot 🥵

[Deleted member 120897]

Greetings members of plumbersforums,

Firstly - long post alert

I’m struggling with my hot water currently - I’ve only mainly dealt with combi boilers, even then, not really had hot water too hot. Anyway I digress, my system is an open vented pre-lagged cylinder, S-plan, Myson 2 ports with a Myson cylinder stat. My hot water seems far too hot, I haven’t measured it recently, but when I did a wholeness back, I was getting 68/69 from being set at 60. I reduced it to 40, and was manageable, but still seemed hot. I’ve been been trying to “test” it today, and wife’s has said it’s gone worse. Here’s what has been done so far:

• Replaced Myson with Honeywell temporary, still same issue (although couldn’t have wired it wrong)
• 2port isn’t firing boiler by itself (that I know of)
• Checked spindle on 2 port - is fine
• Immersion heater isn’t on - checked and double checked
• Checked lever on 2 port head - not fantastic resistance
• 2 port comes on when I turn dial up on stat, and goes off when I turn it down
• Noticed just now, cylinder stat no longer clicking
• When I tested for continuity between orange and grey it brought pump on? But was my multimeter acting as a link?
• Cylinder stat is making good contact, and worked fine for approx 9 years
• Felt tank by stat, seems cold?

I have checked wiring from cylinder thermostat and is as follows:

• Common from programmer goes to terminal 1
• There’s a blue wire (assuming switch live?) in terminal 2
• Nothing in terminal 3

I read it as 3 is call for heat? I asked elsewhere and told call is terminal 2? This is where I’m struggling - can anyone explain it better? Can anyone help me test this properly? Someone has mentioned stratification?

A thanks already in advance

 

[Murdoch]

Not sure if it’s worth mentioning, but I can put my dhw on timer, comes on approx 6am, goes off at 7:45am, will probably last until early to mid afternoon (nobody using it much then). During this timed period, I’ll hear the boiler fire up at least 3 times, is that normal?

how many people in your house? Showers or baths?

using the timer should mean the HW is only heated when the timer tells it to - so if it’s doing HW when the timer is “off” then I’d say you’ve got a wiring issue

 

[Deleted member 120897]

how many people in your house? Showers or baths?

using the timer should mean the HW is only heated when the timer tells it to - so if it’s doing HW when the timer is “off” then I’d say you’ve got a wiring issue

4 (2 adults and 2 children), showers are teatime ish, baths are one every other day for the kids. I don’t think it’s heating it outside of these times, it was more for clarity of how long the hot water lasts. Thanks.

 

[John.g]

how many people in your house? Showers or baths?

using the timer should mean the HW is only heated when the timer tells it to - so if it’s doing HW when the timer is “off” then I’d say you’ve got a wiring issue

Screen just shows time taken to heat from cold (65 mins). cylinder heating times programmed (twice/day) from solar controller.
Two people normally, 3/4, occasional weekends, bath "never" used.

Edit: replied to wrong post.