Boiler help

This looks very much like the water pressure is low.  There is usually a tap near it that you open to let water flow thru to fill it  back up. The gauge shud be about midway?.

I'm not an expert but looks similar to our boiler at home!

Hi , do not have your type of boiler but as per dgiddi the water feed tap may be blocked with limescale , depending on your area but hard water is common in our location which blocks the tap only the same as what is in kettles.

What I would do is just turn the on/off water tap on and of about 6/8 times this may clear but of course not guaranteed.

Another option is the sink taps , on the spout is a removable cap were the water comes out , it has a small mesh/gauze ( as a precaution put the plug in sink as when you take the cap off the small rubber o ring does not get lost) just give it a clean and replace, this may again not be a cure but it is something to at least try before calling tradesman.

Hope it goes well

Is that an electric water cylinder ?

Is that a pressure gauge or a temperature gauge ?

If you open the hot tap, does cold water come out ? If yes, it sounds like an electrical supply problem. Suggest you check the trips in your distribution board first.

Looks like temperature gauge to me, underneath the boiler there maybe a dial that needs turning up ? ( maybe)

A little knowledge ......or so the story goes.

The gauge is temperature not pressure. The BOILER is an unvented water heater and is pressurised by the cold water input. Heats the water like a kettle. Check to make sure the water heater is plugged in or switched on. There is a temperature control on the heater. Mine is underneath. If there is power and still not heating up then its probably an element problem. 

I thank you kind sir 🤣

Cheers Kevin.

The little knowledge gag wasn't directed at you. Yours was the only one close to the mark. 

Lolll yeah I know 👍

My reply was a suggestion merely trying to be helpful, not claiming any expertise. I have no idea about boilers but I do know how to fix the pressure on mine. At the time, no one had answered.