Open system or Not?

corajen

Hi,

I recently had my gas boiler serviced; I asked the plumber how water gets into the system when he cleans the Magnet filter (darning the water out of filter)? how is water replaced.

He said I have a water tank in the attic and if fills automatically. Now I also have a pressure vessel next to the boiler which he said was for the gas boiler (Ideal boiler) pressure release? he said I have an open system? can anyone explain how I have a water tank and a pressure vessel on my heating system. and can the water circulate from the heating system into the tank in the attic and if not why not. forgive my limited knowledge?

kind Regards

dave

youtheman

https://www.boards.ie/discussion/comment/119970501#Comment_119970501

That is called a 'semi closed' system.

My house was built in the 1990, the original boiler was an 'open system'. It had a small header tank in the attic with a 'blow off' or overflow pipe. Had to change that after a few years, and the plumber wanted to install a boiler that was designed for a pressurized system, but he didn't want to risk pressurising up old pipes. So the feed from the header tank was fitted with a 'non return valve', the overflow pipe was removed and he obviously frigged the pressure switch in the boiler so it would run at 0 psig. So basically three options:

1. Open system with header tank in attic and blow off connection. Old technology.
2. Closed system, no header tank, pressurizing connection from mains, and pressure gauge at around 1 bar (15 psig), pressure vessel fitted. Modern Technology
3. Semi Closed System with header tank and non return valve in line, no blow off line, pressure vessel may come with boiler but is redundant, pressure gauge reading zero. Half Way House

monseiur

The feed from the attic tank to boiler may have a non return valve, which basically means that water can enter the system but cannot be pumped back up to tank

corajen

😊 thanks

corajen

Hi, I have a pressure vessel sitting below new boiler was part of old boiler. And there is a header tank on attic. New pipe work installed upstairs and existing pipe work downstairs was replaced a couple years ago. So all pipe work qualcast if that's thd right word basically plastic pipe throughout. I have a three way system ?upstairs, downstairs and hot water , motorised valve and eph controller, stats etc. My issue as tou have stated I have header tank and it seems a redundant pressure vessel. Also as you stated the pressure gauge always reads the same 1 bar. The boiler is just 3 years old 24 kw Ideal boiler. So do you think i have a mesh mash of a system.

Regards

youtheman

https://www.boards.ie/discussion/comment/119976838#Comment_119976838

If your gauge is reading 1 bar then that tends to suggest that you have a sealed system. If you have a sealed system then you must have a top up loop where you can connect the mains to the system to get the pressure back up. Do you have this?. If would have a pressure gauge and a pressure regulating valve and and on/off valve. Do you have this?.

Maybe he converted your system from open to closed (sealed) and just disconnected the header tank and just left it there

corajen

Hi ,

No the headed tank is still connected, the pressure gauge has been in place since the original system and maybe not working. I asked how the water gets back into the system when he removed the Magna filter and cleans and replaces. The plumber said I have a headed tank on he's last service that fills the system automatically. But I'm worried that why do I have a pressure vessel and headed tank? with the pressure vessel redundant. I just don't know what to do , should I confront the plumber (as he installed the new system) and ask why the dual system or maybe get the pressure gauge replaced? where would the non return valve in relation to the header tank?

youtheman

The header tank is there to top up your system as and when required. It also keeps your system pressurised (albeit low pressure equivalent to the head height of the attic tank).

Conversely, if your system wants to relieve pressure the water can't expand back up to the header tank because (i assume) there is a non return valve fitted. Instead the pressure vessel has a diaphragm inside which expands to relieve the pressure (I stated previously in error that this vessel was redundant, it is not). If the pressure builds up so much that the pressure vessel can't cope then you will have a pressure relief fitted.

To confirm that you have a 'semi sealed' system you need to go up into your attic and find the small header tank. There should be NO p[en ended pipe looped across the top of the tank facing down, but you should have a non return valve on the line out of the bottom of the tank. Might be hard to make out the NRV as then are not much bigger than a normal pipe connector.

So it looks like you have nothing to worry about!.

corajen

Thank you for your time and effort most appreciated have a good Christmas 🎄