Gravity Feed Central Heating Pressure

chrislynch8

Hi,

I have a Ferroli SYS 10-30 boiler that is feed by a tank in the attic. My question is in regards to the pressure. When it is running, the pressure as shown on the gauge on the boiler itself is a little over .2 or .3 BAR.

My understanding is that I do not need to "top up" the pressure in this case and it should take care of it itself, but the more I read about the pressure in the boiler, I see references to 1bar or 1.5 bar. I found an online guide for the boiler https://www.ferroli.com/media/1506958409.pdf and this suggests there is a filling loop.

I cannot for the life of me find it. My father and brother have a closed system and the filling loop is next to the boiler and when needed they can top up the pressure.

Can the "system" boiler be a closed or open system?

Chris

rightjob!

chrislynch8 wrote: »

Hi,

I have a Ferroli SYS 10-30 boiler that is feed by a tank in the attic. My question is in regards to the pressure. When it is running, the pressure as shown on the gauge on the boiler itself is a little over .2 or .3 BAR.

My understanding is that I do not need to "top up" the pressure in this case and it should take care of it itself, but the more I read about the pressure in the boiler, I see references to 1bar or 1.5 bar. I found an online guide for the boiler https://www.ferroli.com/media/1506958409.pdf and this suggests there is a filling loop.

I cannot for the life of me find it. My father and brother have a closed system and the filling loop is next to the boiler and when needed they can top up the pressure.

Can the "system" boiler be a closed or open system?

Chris

You more than likely have what is referred to as a “semi sealed” system.
Header tank feeding the system with a non return valve on it to stop it going back up to the tank.

John.G

chrislynch8 wrote: »

Hi,

I have a Ferroli SYS 10-30 boiler that is feed by a tank in the attic. My question is in regards to the pressure. When it is running, the pressure as shown on the gauge on the boiler itself is a little over .2 or .3 BAR.

My understanding is that I do not need to "top up" the pressure in this case and it should take care of it itself, but the more I read about the pressure in the boiler, I see references to 1bar or 1.5 bar. I found an online guide for the boiler https://www.ferroli.com/media/1506958409.pdf and this suggests there is a filling loop.

I cannot for the life of me find it. My father and brother have a closed system and the filling loop is next to the boiler and when needed they can top up the pressure.

Can the "system" boiler be a closed or open system?

Chris

There really is no reason why it cannot be a normal gravity system as the boiler pressure when cold will be exactly the same as with a semi sealed system, if you have a semi sealed system then you will also have a expansion vessel, the vent will be blanked off and as stated above a NRV is fitted in the cold feed make up, when the boiler contents are heating up the NRV will be closed and the expansion vessel will take the expansion. If there is a small leak then the NRV will open and top up the system when the boiler pressure is < than the gravity head and that's why you don't need a filling loop.

chrislynch8

Thanks for the info.

What would the NRV and expansion vessel look like?

Regards
Chris

John.G

chrislynch8 wrote: »

Thanks for the info.

What would the NRV and expansion vessel look like?

Regards
Chris

I can't find a link to your model of boiler (10-30) but it's probable that this has a internal expansion vessel which is obviously inside the boiler casing. If you have a semi sealed system and the NRV is holding then you should definitely see a rise in pressure from a cold to a hot system to the order of = or > 1 bar.
Have a look at the cylinder coil entry on the top, at the side, in most cases the vent from this is carried on and "bent" over the F&E tank, you may find that this pipe has been disconnected at the T piece and the top of the T piece blanked or replaced with a elbow to just feed the coil entry. If you had/have a combined cold feed and expansion then this will not be blanked in this position but have a look at your F&E tank and see if the cold feed (make up) is connected directly into the vent, if so then (if semi sealed) the vent pipe T piece here should have been blanked and the vent removed.
The NRV may be fitted in a horizontal section of the cold feed very close to the F&E and may look like the one in the attachment. IF a external expansion vessel has been fitted (unlikely in your case) then it will look like the one in the attachment, they are generally ~ 8 to 12 litre capacity and may be located anywhere really, in the hot press or loft for example.

Edit: In either instances above, a AAV (automatic air vent) may/should have been fitted where the vent pipe has been disconnected.

Browndoff

Even if the system was originally built correctly, it may have faults now - typically caused by hard water in your neighbourhood.
I had to remove a Non-Return-Valve located [as described above] in a top-up-pipe from the tank to the heater-coil in the hot-water-tank because the limescale had blocked the NRV itself and some of the pipes in the region of the heater-coil. It was a horrible job to clean out those pipes! I had to flush-out the entire heating-system and refill with an 'inhibitor'-fluid.

The symptom? - my hot-water-tank stopped warming-up - now it's fine again!

Any such valve in the area where hot water [from the heating-system] meets cold water [from the top-up-tank in the attic] will be prone to the limescale coming out of solution in the water and fixing itself on the metal surfaces of the valve and the inside of the pipes. A huge proportion of the Irish water-supply is full of calcium-carbonate [limescale] - so it's always a 'likely suspect' in plumbing problems.

agusta

Do you have a large and small tank in the attic

John.G

I have a few neighbors that retrofitted to gas fired systems (all installed by borg gais ) and all these systems were semi sealed with the swing check NR valve mounted (horizontally) close to the F&E tank in the attic, has anyone seen a open vented gas fired boiler?, as when cold the system pressure is exactly the same as in the semi sealed system, ~ 0.5 bar in a two story house with the boiler on the ground floor.

agusta

John.G wrote: »

I have a few neighbors that retrofitted to gas fired systems (all installed by borg gais ) and all these systems were semi sealed with the swing check NR valve mounted (horizontally) close to the F&E tank in the attic, has anyone seen a open vented gas fired boiler?, as when cold the system pressure is exactly the same as in the semi sealed system, ~ 0.5 bar in a two story house with the boiler on the ground floor.

John, i have a house that has a open vented system with a gas boiler. House 2004, baxi solo boiler,no pressure gauge on boiler.Still working away,no issues

John.G

agusta wrote: »

John, i have a house that has a open vented system with a gas boiler. House 2004, baxi solo boiler,no pressure gauge on boiler.Still working away,no issues

Very good, hence my query, maybe its because when installers see a integral E.vessel fitted that they think that it must be in conjunction with a sealed or semi sealed system, seems a bit daft to me.