Fill Loop - Consequences.

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SirLancelot

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Exploratory Topic. Interesting scenario.

Main combi 25 Eco.

Air in rads - so bled.

CH circuit topped up - BUT forgot to reisolate @ fill loop!

Boiler had mains fill loop left open for about a month. Presure Dial on boiler showed close to 2/2.5 bar before problem was discovered. Boiler was running during this period.

A gas safe certified engineer will be servicing the boiler. It is in a family home - so this is non-negotiable.

Question:

Given the scenario above - what needs to be checked. What parts are likely to have been damaged. Boiler has run for two years after this event. Recently pump gave out.

No system filter on CH system.
 
1. If its worked for 2 years after the event, probably nothing wrong with it, unless constant "topping up" was required.
2. Pressure dial could easily go to 2.0 hot on a system with 1.5 bar cold.
3. Service should include check on expansion vessel anyway. Might be worth asking for PRV to be inspected to see if it has operated.
4. Worth fitting a filter on the return close to the boiler. Make sure inhibitor is added as part of service.
 
Only problem is the boilers Pressure releif valve may be crusted up and will need cleaned/replaced, hardly a big deal
 
Update/clarification:

When the open fill loop was discovered - the "pressure meter dial" on the boiler was in the red. But crucially, NOT at its furtherest extreme. It was not "topped out".

This will have been for the duration the boiler was left in this situation (roughly 1 month).
 
SirLancelot said:
Update/clarification:

When the open fill loop was discovered - the "pressure meter dial" on the boiler was in the red. But crucially, NOT at its furtherest extreme. It was not "topped out".

This will have been for the duration the boiler was left in this situation (roughly 1 month).
Click to expand...

It will not have "topped out", as when reaching 3bar, the PRV would open releasing the water and pressure. Presumably, you have had water running from PRV the whole time. Is the PRV outlet clearly visible
 
Last edited:
Also - I have been told that leaving the fill loop open means excess oxygen would've also been introduced to the CH system.

That any inhibitor would've been flushed out of the PRV. And that the result would've been excess corrosion?
 
Well in that case replace all pipework, all radiators and fit a new boiler, OR check the PRV and add inhibitor, your choice
 
This is where I'm at currently.

I'm fearful of using a powerflush, as most of the pipework is behind plasterboard.

What do you think about the following:

A) Clean out the existing plate heat exchanger (SoS) & replace.

B) Have PRV checked and replaced (if necessary).

C) Drain out the CH system, then flush through the fill loop.

C) Take of rads and flush thoroughly & replace.

D) Add a system filter to the return loop on boiler.

E) Add system cleaner and run CH for a couple weeks - observing the system filter.

F) Drain & replace CH system - adding inhibitor.

This is a draft procedure - I am directly asking for advice and guidance on how to
improve and refine it.
 
Why not just bleed some water out of the system until pressure gets to whatever is normal for your systems and run for a week or two to see if everything is okay pressure and performance wise. If it is, fit a system filter and add inhibitor? I wouldn't think having the system flushed would be needed but I'm no heating engineer.
 
SirLancelot said:
Also - I have been told that leaving the fill loop open means excess oxygen would've also been introduced to the CH system.

That any inhibitor would've been flushed out of the PRV. And that the result would've been excess corrosion?
Click to expand...
oxygenated water will only have been introduced if prv had actually opened you dont know if it actually did
 
SirLancelot said:
This is where I'm at currently.

I'm fearful of using a powerflush, as most of the pipework is behind plasterboard.

What do you think about the following:

A) Clean out the existing plate heat exchanger (SoS) & replace.

B) Have PRV checked and replaced (if necessary).

C) Drain out the CH system, then flush through the fill loop.

C) Take of rads and flush thoroughly & replace.

D) Add a system filter to the return loop on boiler.

E) Add system cleaner and run CH for a couple weeks - observing the system filter.

F) Drain & replace CH system - adding inhibitor.

This is a draft procedure - I am directly asking for advice and guidance on how to
improve and refine it.
Click to expand...
Do the radiators heat up all over with no cold spots . if yes then no need for c, c,d,e,f
 
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