Magnetic filter position?

[Tim Hu]

Hi.
This is my first post so please be gentle!
We recently moved into a new house and the central heating system was almost not working. We had a plumber round who recommended a power flush. We did this and he said it was one of the worst he had seen. He recommended another clean next year.
Having researched online I've found that our best bet now is to fit a magnetic filter. I'm struggling to figure out where a magnetic filter could go on our heating system. We have an oil boiler. The return pipe goes into the top of the boiler, and there is only an 18cm ish gap between the top of the boiler and the ceiling. I saw the Adey vortex 250 filter which is good for compact spaces, and might just fit. I then saw the return pipe above is a 28mm pipe, and the vortex 250 fits 22mm pipe. I am unable to find a suitable filter to fit here so was thinking the airing cupboard is the next option.
I have attached a pic. We have an extension so there are 2 return feeds going into a single boiler return pipe (all 22mm) in airing cupboard. I have attached a pic. Red vertical arrow is boiler feed pipe, red horizontal arrows are 2 central heating feed pipes. Blue arrows are central heating returns and boiler return pipe. My questions are:
1. Where would be the best place to install a magnetic filter? Could I extend the 2 central heating return pipes upwards to create a big enough gap between them and the main boiler return to fit a filter?
2. The yellow arrow. Is this a bypass valve? If yes, can the filter go before this or does it need to go after this?
Thanks in advance for all advice.

 

[fixitflav]

I then saw the return pipe above is a 28mm pipe, and the vortex 250 fits 22mm pipe. I am unable to find a suitable filter to fit here so was thinking the airing cupboard is the next option.

Fitting a 28x22 reducer wouldn't be a problem flow-wise, but then there'd be even less room.

We have an extension so there are 2 return feeds going into a single boiler return pipe (all 22mm) in airing cupboard.

I assume there are no more rads returns coming in below the airing cupboard, as this would break the rule all rads returns must be commoned before the cylinder return joins.

Could I extend the 2 central heating return pipes upwards to create a big enough gap between them and the main boiler return to fit a filter?

In principle, but it would be quite fiddly.

The yellow arrow. Is this a bypass valve? If yes, can the filter go before this or does it need to go after this?

Doesn't matter

The usual place for a filter is the CH return, so it stops crud entering the boiler. I suppose the pipe with the red arrow going straight up is the boiler flow. Don't know what the pros on here think, but putting the filter in that line is an option. It would still do some good and the system has managed without one for years.

Where are the open vent and cold feed, above the pic, maybe in the loft? Pumping downwards isn't ideal. With open vent and cold feed rearranged the pump could go in the upward pipe.

With the pump where it is the power lead going in the top isn't ideal. The flow direction is determined by the pump body, not the motor, you could rotate the motor 180°, just 4 Allen bolts.

 

[gas112]

The thing about sticking it on the return is purely a sales pitch the filter doesnt collect a great deal on first pass of water so it actually passes through the boiler thousands of times a day god knows how many millions of times in a year so if you can get it onto the flow before the pump then this will be perfectly ok .

 

[Tim Hu]

Thank you both for the replies. It is greatly appreciated. I think it might be best putting it before the pump, as you say gas112.
Fixitflav - yes, the cold feed is in the loft. I am not sure whether there are any more radiator reforms between the airing cupboard and boiler, but I would guess not. It looks to me like the central heating for the extension feeds into a common return here before returning to the boiler, but I can't be 100% sure.
It's good to know about the motor lead. This was recently replaced by a local plumber so I assumed it was correct.

 

[fixitflav]

yes, the cold feed is in the loft.

I meant where does it, and the open vent, connect to the circuit. But if the system works OK probably not worth worrying about pumping downwards.

I am not sure whether there are any more radiator reforms between the airing cupboard and boiler, but I would guess not.

If there are, the some rads will get warm when HW only called.

It's good to know about the motor lead. This was recently replaced by a local plumber so I assumed it was correct.

The terminal box is fitted so the lead is into the bottom when pumping upwards, that's why the writing is upside down. The plumber could have done the 180° turn before fitting the pump. It's not a big deal, but if the system is drained to fit a filter it could be done then.

 

[Tim Hu]

Hi fixitflav.

I meant where does it, and the open vent, connect to the circuit. But if the system works OK probably not worth worrying about pumping downwards.

I've attached a pic. 22mm pipe at the back of the pic is the boiler feed pipe coming up from the floor (the one with the red vertical arrow in the previous pic). The 15mm pipe above this is the overflow/vent. The pipes at the front of the pic are the cold feed and CH feed. This pipe goes down into the pump.
I've read that this area can accumulate junk so I've put a magnet on this section and it is magnetic indicating there's a build up here (the system has been pumping over to the loft tank). I think I'll put the filter here as can't find anywhere else to put it, and can also clean this section whilst I'm there.

 

[dilalio]

If your boiler allows it, I would consider sealing the system.

 

[fixitflav]

I've attached a pic. 22mm pipe at the back of the pic is the boiler feed pipe coming up from the floor

Did you mean the boiler flow pipe?
I wouldn't pipe the open vent like that, across the top of a tee, as it gives a head start to water into the vent, encouraging overpumping. Better to take the vent from the top of a horizontal run.
I would do it like the attached sketch, the cold feed up and under, to reduce convection warming the F/E tank aiding algae growth. The filter could go in the boiler flow, before the vent, or after the pump, whichever is easier.

 

[dilalio]

Did you mean the boiler flow pipe?
I wouldn't pipe the open vent like that, across the top of a tee, as it gives a head start to water into the vent, encouraging overpumping. Better to take the vent from the top of a horizontal run.
I would do it like the attached sketch, the cold feed up and under, to reduce convection warming the F/E tank aiding algae growth. The filter could go in the boiler flow, before the vent, or after the pump, whichever is easier.

I have never seen one done that way, in the wild. Not denying it makes sense but, never seen it.

 

[fixitflav]

I have never seen one done that way, in the wild. Not denying it makes sense but, never seen it.

Boiler installation manuals, if they include a piping layout, usually but not always, show cold feed up and under. The thing about not taking the vent from across the top of a tee is my own idea, but I believe it reduces the tendency to overpump.