Mixer shower lukewarm water and boiler pressure kot rising when I open the valve

[Flippingheckwtf]

Can anyone advise on this? Been having lukewarm showers recently, sink water in bathroom is not bad if I let it run and kitchen water gets hot enough for washing dishes. Google told me I have a mixer shower not electric like in my old place. I read something about a cartridge needing replacing but don't know for sure. My boiler pressure is also not rising when I open the valve like I was shown by my dad years ago. He's gone now. The valve doesn't seem to be working as it's not making the same noise it used to when it opened.

I'm not great with household appliances and the boiler scares me a bit tbh but I'm assuming the problem is linked. Do I need to get in a plumber and/or boiler engineer?

Thanks for any advice.

Could be a diverter valve not opening for the hot water problem. Is the mains water pressure down? That may be why the boiler pressure doesn't go up when you open the valve, as far as I'm aware you are pressurising it off the water main pressure. It could be the water board has turned the pressure well down due to the drought.

Do you have a back up immersion heater in the hot water tank? We have (if I can ever find the switch to turn it on) we had a similar problem with a diverter valve and used the immersion heater while getting the bits to fix it.

Edit: No plumbing required for diverter valve, just finding it and a screw driver.

If it's a combi boiler the pressure gauge is for the central heating circuit,so doesn't change when you use hot water. Thermostatic mixer valves do get stuck especially if you have hard water, try briskly turning the adjust end to end a few times or give it a good whack, if that doesn't fix it you need a plumber, though I'm sure if you're confident and have the tools you could do it yourself with the aid of the internet.

Thanks both. I don't have an immersion heater or hard water. Am in Scotland. I'd read online about a cartridge thing that can get blocked etc so maybe it’s that. Or the valve. Definitely not confident with this stuff. I just walked past a local plumber/heating engineer van so might try them. So annoying when things don't work but hopefully get it fixed soon.