pressure rise with dhw

[lost]

Hi

After using hot water a few times today (taps and shower) while the central heating was off, we noticed the pressure on the boiler rising. it was at 1.2 initially. When hot water turned on, burner fired up and pressure dropped (as it normally does to 1.1 ish). On turning hot water off, needle went back up to 1.2 ish and then continued to rise to 1.3.

the 22mm heating pipe next to the 15mm hot water supply pipe was hot at the top near where it is attached to the boiler. The rest of the pipe was cool. Is it normal for the heating pipe to warm up slightly at the top. is this what's causing the pressure rise? do i have a problem?

Thanks in advance for any suggestions.

 

[stevetheplumber]

yes perfectly normal as heat from boiler is dumped into heating circuit by pump overrun
slight change in preasure is also caused by pump and water in boiler expanding then contracting

 

[Mbear]

Why do folk question it when their boiler is working spot on.

I'm only kiddin but don't look for problems that aren't there. If you've got a real problem you'll soon know about it as you'll be either freezing or unable to wash or worst both.

 

[oldplumber]

why was ilewis banned for asking the same question 23 hours back? did you get your name changed by deedpole? or you a rising phoenix poping up again to get the same answers given to you