Grant boiler. Oil heating. Low pressure

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Hi all! Not sure if this is the best place to put this? We have moved and I'm at my wits end with this boiler. It's a gran 90/120 boiler and the pressure for hor water is so low. I have bled all the radiators and it's not related to that.

I have googled and googled and everything tells me to.turn the 2 black valves to up the pressure then tur them back. It when I do this, nothing happens. Estate agents are closed. We just need a hot shower without the water turning off every 2 minutes. I can't wash up. I can't afford a plumber myself as we have just moved in!

Hoping someone can help or guide. May e I'm doing it wrong. How do.yky put the pressure up
?

Never mind! I worked it out!

I am not a plumber but if you bleed the rads then you’ll drop the pressure. You need to put more pressure (I.e. water) back in to the system to rectify this. There’s usually a little tap on the pipes that run to the boiler itself. I had to do it myself in the past and would top it up until it reached 2.5bars.

Ffs, just realised it’s an old thread 🙈

Thanks all. Turned out to be a broken inner steel pipe. All fixed now! We also rent so couldn't have made any changes.