air entering the system gravity fed oil boiler

[Dorr69]

Hi
I have a pretty old heating system though the boiler is only 2 years old after replacing the old 25 year old one
It has a hot water tank and a header tank above it in the loft
I’ve always had problems with the system being noisy on the first two rads to the extent I can’t turn my son’s bedroom rad on when he is in bed as the noise of air rattling in it is so loud it wakes him
When you turn the heating on you can hear water tricking in the header tank abc air rattling through the pump
Is it a common problem with gravity fed systems ?
There is no zone valve when the boiler is required for hot water, it’s set up so the pump doesn’t turn on therefore heating the water in the tank by gravity
I’m forever bleeding the system
I can bleed the air from the first two rads only to hear the air trickling back into the first rad again

 

[Gasguru]

Gravity hot water in 2018
Get the system properly re-piped...fully pumped on S plan.
Whilst they're at it re-configure the pipework or clear the blockages...there should be no water circulating round the vent pipe or air ingress.

 

[Dorr69]

Thank you gas guru
In the meantime do you think I should put some cleaner through the system and flush the remove and flush the rads ?

 

[dilalio]

Thank you gas guru
In the meantime do you think I should put some cleaner through the system and flush the remove and flush the rads ?

If the rads are heating up then that's not going to do much IMO.
Pump position, feed and vent location and configuration are all contributing factors to air being drawn in. Also new boiler might require smaller bore pipework where you probably have the existing large bore network for primaries. There's too much to consider on this medium and a proper on site appraisal is required really.
You "might" benefit from combining the feed and vent from the f&e but this depends where it Tees into the system and where the pump is in relation to that.
Post some pics of that part of system and we may have some ideas.

 

[Dorr69]

Thank you
I’ll take some pics when I get home later

 

[oilhead]

Also, what speed is the pump on? If on 3, then turn it down. This may be sufficient for flow, and may stop the ingress of air.

 

[Dorr69]

 

[dilalio]

Can't make out where feed and vent is but pump is incorrectly oriented.

 

[ianmcd]

your pump is incorrectly installed

 

[Dorr69]

Pump incorrectly installed in what way ?
I’ve turned the speed down to two
If I turn it to one will the water be hotter at the rads ?

 

[Gasguru]

What a mess...fire valve installed inside the property, pump spindle vertical, cylinder next to boiler.
Is that boiler even approved for gravity operation?

 

[Dorr69]

I really couldn’t tell you
As I said it’s an old set up but a new boiler two years ago which was fitted and plunged like for like
No tank stat no zone valve

 

[Gasguru]

I haven't worked on oil for 20 years but the purpose of the fire valve is to shut the oil supply off when the sensing bulb gets too hot ie. if there's a fire. The part in the corner should be outside the house. Who installed the boiler?
The pump spindle must be horizontal..look at the manual. Currently it won't vent properly and the bearings will be damaged. What way is the arrow on the pump back casing facing?
Gravity circulation relies on a sufficient vertical distance from heat source to cylinder...that boiler must cycle on/off forever trying to establish circulation.
What's the boiler make and model?

 

[oilhead]

There are instances where a remote acting fire valve can be installed inside. Something is better than nothing. DHW must obviously be by convection rather than gravity circulation, and there are plenty of old systems just like this.
Why wouldn't this boiler be suitable for gravity DHW?
Easiest and cheapest fix would be converting to fully pumped, but looking to future and knowing OP has only just moved, a full new system could use this boiler, but benefit from a new cylinder and fully pumped, repositioning pump and more effective controls.

 

[Dorr69]

The fire valve was installed two years ago with the new boiler
It didn’t have one before
It’s a firebird 90 boiler I think
The HW tank looks very old
I’ve just fitted a nest thermostat onto it for better controls and it’s wkrking great
But I think I it needs seriously updated with an s system
The HW is beside the boiler on pallets but would’ve been. Fitted in the early 70’s
When the heating is on we have plenty very hot water
The big large copper pipes from the boiler go into the ground and are concreted
So an s type system would be more efficient on the boiler and hot water side ?