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Hoping to open up a technical discussion regarding best practice with Y-strainers (also spelled wye – strainer) on domestic CH systems.

I’m hoping this thread can be a general discussion to explore this topic & share any insights members might have. I’d like to flesh this out - so newbies can enlighten themselves too.

(Assume the Y-strainer is fitted in addition to a mag CH system filter).

Stating the obvious - Two types of debris in CH water - magnetic & non-mag.

Magnetic system filters generally deal with the mag debris VERY well e.g magnaclean, spirovent etc. However - this is not always the case for non-magnetic particles

This is where Y-strainers can help. Essentially it's a sieve that collects muck - using a simple stainless steel gauze. They can be placed inline on both the, coldwater fill & CH return loop:

How it works



Filter.png


Pressure drop.png


Important:

1) They cause a pressure drop in the loop - so step up one/two sizes to increase the surface area of the gauze.

2) They need to be isolated - before & after the valve - so that the gauze can be extracted & cleaned (freq depends on how dirty the water is).

3) The only real way, to be able to see when it’s blocked – is to have pressure gauges installed inline too - to assess the change in pressure across the guaze.

Any contributions regarding the basic primer above, is most welcome.

More technical questions for expert members:

A) Gauze/strainer hole size - What is the best correct size to aim for. I've seen y-strainers with gauze as fine as 50 microns available for domestic CH.

B) Are there any strainers that are designed for upward flows - instead of just the horizontal or downward flow ones you can get from toolstation etc.

C) If the gauze does get blocked - do most boilers have a safety mechanism that will simply shut down the pump until the blockage is resolved? I.e if the strainer gets blocked - will it cause irreparable damage to the boiler?

My sincere thanks to anyone willing to contribute to the discussion.

Disclaimer: Yes – in a properly cleaned system that is well installed/maintained – a Y-strainer should not be necessary. However – it is still a good insurance policy – given that they are so cheap. E.g My Ecotec 837 – does not have an inbuilt strainer fitted before the heat exchange. On very rare occasions - it has been known for debris from street level repair works – to work its way into household water supplies. So – This discussion is to focus on those scenarios where a Y-strainer is actually worthwhile – or is at least a sensible precaution – or even as an additional filter.
 
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All sorts of magnetic filters have non magnetic strainers ....centramag by Trappex is one of the best ...in both areas...at the end of the day ...any filter anywhere house car etc is only
at its best when cleaned or replaced so, why have two when one good unit will do ? I have
a long history in designing these filters...but not the centramag thats why I can mention it.
centralheatking
 
I will address question (C). When flow is reduced significantly the water cannot carry the heat away from the boiler and the high limit thermostat will cut the heat off to prevent damage. No different to a failed circulating pump situation. Some boilers will also monitor flow rates and detect problems and shut off the heat too so in either case a boiler in good working order will not be damaged by a blocked strainer.
 
I have often wondered about this system on a few of my systems where I am pretty sure most of the **** is coming off towel rails and ending up in the boiler .
Depending on how much non-metalic **** is in the system I doubt if a gauze filter will get through a full year between services so consequently may result in more call backs .
 
I think you are correct on both points there. There has to be a point where a certain amount of small solids must be allowed to circulate otherwise the thing is going to block too frequently.

I have an on topic question. What is the smallest waterway size to be found in anywhere in any commonly used heating system? Knowing the smallest bore a particle has to navigate would help to determine the best size for a course strainer and gain some balance with regard to overdoing it and it needing too much maintenance.

The waterways in heat exchangers are probably the smallest in a system I suspect.
 
I think you are correct on both points there. There has to be a point where a certain amount of small solids must be allowed to circulate otherwise the thing is going to block too frequently.

I have an on topic question. What is the smallest waterway size to be found in anywhere in any commonly used heating system? Knowing the smallest bore a particle has to navigate would help to determine the best size for a course strainer and gain some balance with regard to overdoing it and it needing too much maintenance.

The waterways in heat exchangers are probably the smallest in a system I suspect.

Plate heat exchangers the worst , literally millimetres between the plates .
 
I know that some of the performa boilers had a strainer/gauze fitted on the return manifold from factory. So clearly there is a justification for the use of strainers to protecting the boiler.

The issues are how it should be done best. Hence me bringing up this topic.

I have a vaillant ecotec 837, which apparently has a plastic filter fitted inline - inside the boiler to protect the pump - but there is none before the heat exchange!!! Obviously there should be one before it - surely.

The question of pressure drop is an important one - no point trying to protect the boiler with a strainer - if a pressure drop causes serious damage (as the gauze gets blocked). Unless of course the boiler has a protection mechanism - to switch off the flow - in which case - you'll know that something needs working on.

At the moment - the consensus seems to be to go up in size (increase surface area of strainer) but its the size of the mesh that hasn't been really discussed.

Open to any contributions...
 
I know that some of the performa boilers had a strainer/gauze fitted on the return manifold from factory. So clearly there is a justification for the use of strainers to protecting the boiler.

The issues are how it should be done best. Hence me bringing up this topic.

I have a vaillant ecotec 837, which apparently has a plastic filter fitted inline - inside the boiler to protect the pump - but there is none before the heat exchange!!! Obviously there should be one before it - surely.

The question of pressure drop is an important one - no point trying to protect the boiler with a strainer - if a pressure drop causes serious damage (as the gauze gets blocked). Unless of course the boiler has a protection mechanism - to switch off the flow - in which case - you'll know that something needs working on.

At the moment - the consensus seems to be to go up in size (increase surface area of strainer) but its the size of the mesh that hasn't been really discussed.

Open to any contributions...
I have when got time looked at the practicalities of installing a sacraficial hex outside the boiler which could easily be wipped out cleaned an put back in or replaced thereby
protecting the one in the boiler...they are really quite cheap as a sep unit
centralheatking
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I know that some of the performa boilers had a strainer/gauze fitted on the return manifold from factory. So clearly there is a justification for the use of strainers to protecting the boiler.

The issues are how it should be done best. Hence me bringing up this topic.

I have a vaillant ecotec 837, which apparently has a plastic filter fitted inline - inside the boiler to protect the pump - but there is none before the heat exchange!!! Obviously there should be one before it - surely.

The question of pressure drop is an important one - no point trying to protect the boiler with a strainer - if a pressure drop causes serious damage (as the gauze gets blocked). Unless of course the boiler has a protection mechanism - to switch off the flow - in which case - you'll know that something needs working on.

At the moment - the consensus seems to be to go up in size (increase surface area of strainer) but its the size of the mesh that hasn't been really discussed.

Open to any contributions...
I am at Phex tomorrow and will find out from Shaz at Centramag what mesh size he would use...is it expressed in denier like womens tights ? A loaf of old bread without the crust stuffed into womens fine mesh tights used to get the red in diesel out ...I was told !
centralheatking
 
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I think you are correct on both points there. There has to be a point where a certain amount of small solids must be allowed to circulate otherwise the thing is going to block too frequently.

I have an on topic question. What is the smallest waterway size to be found in anywhere in any commonly used heating system? Knowing the smallest bore a particle has to navigate would help to determine the best size for a course strainer and gain some balance with regard to overdoing it and it needing too much maintenance.

The waterways in heat exchangers are probably the smallest in a system I suspect.
Plate heat exchangers the worst , literally millimetres between the plates .

I think you've both honed in on two key aspects in selecting a Y-Strainer/mesh.

I am beginning to come around to the idea that there is definitely a place, for a properly chosen/installed Y-Strainer on the CH return loop - if it can be easily cleaned out when needed.

I've been wondering (even with the ones that effectively capture NON-mag debris) how much they capture on the first/second pass? Furthermore - how many passes would need to be made by the body of water in the system - to get it clean?

If the debris does pass through the heat exchange a few times, before the particle happens to hit a low pressure zone in any system filter - it would mean a fair bit of debris passed through the boiler exchange - before it got the chance to be filtered out.

Surely with the addition of an appropriate Y-strainer - on the very first pass - would capture a massive amount of all this debris - preventing it ever passing through the boiler even once?

I'm exploring Y-strainers as an additional measure to a proper system/mag-filter - not in replacement of them.

The key decisions here seem to be (correct me if I'm wrong) - in choosing the appropriate gauge of mesh/filter and then in ensuring there is enough surface area with the mesh - so that the system can run for a longer period between clean-outs? Or am I missing something?

centralheatking - any feedback from shaz on mesh gauges?

Open to any contributions, ideas thoughts from fellow members ......


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A strainer could be installed in conjunction with a valved bypass so it could easily be isolated and cleaned. The strainer could even only be connected to the system for the first X amount of days before being removed and cleaned. Then you run the system through the bypass and not the strainer in normal use. You can bring the strainer back inline any time you wanted to. If any work is done on the system, soldering or cutting, new components fitted or replaced on the system and you are worried about particles of a certain size entering the system just bring the strainer back in for a while.

Now, I reckon I might be over thinking this but it would not hurt a heating system to have it in place at least. I see it as something that an enthusiastic homeowner who takes a lot of interest in their house's systems might like. I don't think it's something that would make it into every system in then country like magnetic cleaning will probably do one day.

That doesn't mean it is a bad idea though and if someone wants to spend the money and effort and they are happier for it nothing wrong with that.
 
Can any recommend a supplier for a 28mm Y-Strainer (Compression fittings) - that also supply a 50 micron mesh (even if the mesh has to be purchased separately)?
 
Are you really thinking about putting such a system into your heating circuit? What are your thoughts at this point after this further discussion?
 

Just need some 1-22mm comp Male irons

Won’t need anything finer than 500 micros only use 50 microns on a drinking supply
 
Unusual to require a strainer either Y or witches hat in a domestic heating system on anything other than a temporary basis for specific cleaning.

The reason being that the pressure drop across the stainer (particularly on small bore pipework) can be quite high - hence the use of a witches hat strainer.

To instal it properly, it should have a sensor to measure the pressure drop across the strainer to signal when cleaning is required or to shut off the boiler.

There are far more cost effective ways of cleaning a system.

Also be aware that with fine mesh filters the quality is vitally important - if the filter mesh brakes away in service ( which is not uncommon) - it can cause more problems that it solves.

Please don’t read this as being negative, but in design terms on hydraulic (water and oil) systems you only instal filters when the systems dictates that they are needed. You should not instal them as a “nice to have”
 
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We would always install them in a commercial applications to protect the boilers, I have even fitted a few after a mag filter on problem systems especially with Glowworm boilers which were our go to boilers when I was working on the books, the flow sensors were a nightmare if a small amount of dirt got through so in the right application there is still a place for the y type stainer look at the boss brand online . Kop
 
Plate heat exchangers the worst , literally millimetres between the plates .
Finding Sometime almost impossible to clean using chemicals and rinsing through the ports with water
 
Had a few times both on pottos 24combi golds. Had to purchase and exchange. What's the chemical salt you used?? Mines corgi melt. Cheers
 
Spirit of Salts is Hydrochloric Acid. I think that Kilrock drain cleaner is predominantly hydrochloric acid.

Very effectice, but be very careful when using it - not just for skin burns, but inhaling the fumes is very unpleasant.

I am surprised that they sell it over the counter / ebay.
 
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A strainer could be installed in conjunction with a valved bypass so it could easily be isolated and cleaned. The strainer could even only be connected to the system for the first X amount of days before being removed and cleaned. Then you run the system through the bypass and not the strainer in normal use. You can bring the strainer back inline any time you wanted to. If any work is done on the system, soldering or cutting, new components fitted or replaced on the system and you are worried about particles of a certain size entering the system just bring the strainer back in for a while.

Now, I reckon I might be over thinking this but it would not hurt a heating system to have it in place at least. I see it as something that an enthusiastic homeowner who takes a lot of interest in their house's systems might like. I don't think it's something that would make it into every system in then country like magnetic cleaning will probably do one day.

That doesn't mean it is a bad idea though and if someone wants to spend the money and effort and they are happier for it nothing wrong with that.
Hi Stig, unfortunately with regard to homeowners (just like car owners) expecting enthusiasm with regards to maintenance is only really for the minority. Its just a box on their wall even less considered than their vehicles ..which can look quite sexy.
I can see a time soon when boilers will be leased just like most of new cars and mobile
phones. Bring it on more servicing and opportunity for your approach.
We were toying with an optical sensor fitted on the return last June at a meeting with
Teddington Systems ....its really their area of speciality.
centralheatking
 
A strainer could be installed in conjunction with a valved bypass so it could easily be isolated and cleaned. The strainer could even only be connected to the system for the first X amount of days before being removed and cleaned. Then you run the system through the bypass and not the strainer in normal use. You can bring the strainer back inline any time you wanted to. If any work is done on the system, soldering or cutting, new components fitted or replaced on the system and you are worried about particles of a certain size entering the system just bring the strainer back in for a while.

Now, I reckon I might be over thinking this but it would not hurt a heating system to have it in place at least. I see it as something that an enthusiastic homeowner who takes a lot of interest in their house's systems might like. I don't think it's something that would make it into every system in then country like magnetic cleaning will probably do one day.

That doesn't mean it is a bad idea though and if someone wants to spend the money and effort and they are happier for it nothing wrong with that.

This is exactly the approach I'm exploring. Putting the strainer in and cleaning it frequently for the first week or so. I would step up a bore size (from 22mm to 1"/28mm) to compensate for the pressure drop accross these units inline (clean mesh).


Just need some 1-22mm comp Male irons

Won’t need anything finer than 500 micros only use 50 microns on a drinking supply

ShaunCorbs - you've hit upon a key point of discuission. I'm asking for all those contributing to this thread - to help us newbies' expand our horizons. What considerations need to be taken into account when choosing mesh size??? What factors need to be considered - and how should that judgement be formed? I'm after what process should be followed - in order to come to an informed/correct decision on mesh size?

(Also - can you help me to understand why 500 micros is appropriate here - as it will help me finalise my purchase.)

Unusual to require a strainer either Y or witches hat in a domestic heating system on anything other than a temporary basis for specific cleaning.

The reason being that the pressure drop across the stainer (particularly on small bore pipework) can be quite high - hence the use of a witches hat strainer.

To install it properly, it should have a sensor to measure the pressure drop across the strainer to signal when cleaning is required or to shut off the boiler.

There are far more cost effective ways of cleaning a system.

Also be aware that with fine mesh filters the quality is vitally important - if the filter mesh breaks away in service (which is not uncommon) - it can cause more problems that it solves.

Please don’t read this as being negative, but in design terms on hydraulic (water and oil) systems you only install filters when the systems dictates that they are needed. You should not install them as a “nice to have”

Brambles - Thank you for this insight - it never even occured to me that the mesh screens could/might break away in use. In such a scenario - the mesh would represent an even bigger threat to the system, than the debris the strainer was meant to keep out.

I'm going to ask for some help recommending a manufacturer of a Y-Strainers. I know somebody recommended the Boss brand - but I'd like input from others too.

(Just for the record - the y-strainers from tool-stationare very poor. I'd sincerely recommend that anyone buying these thoroughly inspect the insides of those units. At three different toolstations, each of the units they showed me, had brass burr's inside from the milling/drilling used to finish the pieces. These burrs were past the mesh filter - so would break off and flow onward in any system.)
 
Axium or Filterhousings in Warrington will either have a stock product or manufacture one for you. The industry sector to look at for high quality small bore Y or witches hat filters is food processing.

Just be aware that high quality filters are expensive. CHK will have a much better understanding of the market than I do - but I guess that is why so much development work went into the existing range of magnetic filters et al marketed for domestic heating systems.

Even in ground source heat pumps, where water cleanliness is a key issue, we are very careful about how / where and why we instal filters.
 
Axium or Filterhousings in Warrington will either have a stock product or manufacture one for you. The industry sector to look at for high quality small bore Y or witches hat filters is food processing.

Just be aware that high quality filters are expensive. CHK will have a much better understanding of the market than I do - but I guess that is why so much development work went into the existing range of magnetic filters et al marketed for domestic heating systems.

Even in ground source heat pumps, where water cleanliness is a key issue, we are very careful about how / where and why we instal filters.
To be Honest Brambles, when we did the first mag filters it was open season, there were
none, then the market sharpened up thats when Api 2006 got involved to design and
produce manufacture and market & sell increasingly better ones. The main game was
stronger mags and robust fittings ...then we did the vortex ones. The market is saturated now, there are plenty of good ones but Centramag by Trappex is way in front...and I DiD
not have hand in it. centralheatking
 
(Went into B.S.S - quote for a 1" BOSS Y-Strainer = £99. Overkill for my setup.)

So, as this thread is an a exploratory/discussion thread, I'm going to ask the following:

'What is the correct way/procedure to follow, to choose the appropriate strainer mesh perforation, for any install?'

Shaun suggested that 500 microns would be correct for my situation, with 50 microns only suitable for drinking water.

How can we best choose the correct mesh, for any given usage?
 
This is exactly the approach I'm exploring. Putting the strainer in and cleaning it frequently for the first week or so. I would step up a bore size (from 22mm to 1"/28mm) to compensate for the pressure drop accross these units inline (clean mesh).



ShaunCorbs - you've hit upon a key point of discuission. I'm asking for all those contributing to this thread - to help us newbies' expand our horizons. What considerations need to be taken into account when choosing mesh size??? What factors need to be considered - and how should that judgement be formed? I'm after what process should be followed - in order to come to an informed/correct decision on mesh size?

(Also - can you help me to understand why 500 micros is appropriate here - as it will help me finalise my purchase.)




Brambles - Thank you for this insight - it never even occured to me that the mesh screens could/might break away in use. In such a scenario - the mesh would represent an even bigger threat to the system, than the debris the strainer was meant to keep out.

I'm going to ask for some help recommending a manufacturer of a Y-Strainers. I know somebody recommended the Boss brand - but I'd like input from others too.

(Just for the record - the y-strainers from tool-stationare very poor. I'd sincerely recommend that anyone buying these thoroughly inspect the insides of those units. At three different toolstations, each of the units they showed me, had brass burr's inside from the milling/drilling used to finish the pieces. These burrs were past the mesh filter - so would break off and flow onward in any system.)

Let’s put it this way 500 microns is 0.5x0.5mm mesh squares

Nothing is going to get through that and harm your system

50 micron is 0.005x0.005mm mesh squares
 
If you were looking at a commercial system, you would take a fluid sample - and determine the filter size to remove no more than 75% of the suspended solids on three passes.

The problem with a domestic heating system is that the majority of the solids are static - in that the systems are not ( no disrespect to anyone in the domestic heating sector) designed to maintain a constant velocity. As soon as the velocity falls, the solids drop. Indeed, it would not be cost effective to design and implement a domestic heating system to be hydraulically efficient. You just need it to be optimised in a cost effective manner

As a consequence, once the system is clean and properly dosed, filters and traps et al are quite effective. However, they are most unlikely to effectively clean an existing dirty system.

Apologies for being pedantic, but in general terms for small bore hydraulic systems you filter / control the input, not the circulating fluids.

Sorry
 
(Went into B.S.S - quote for a 1" BOSS Y-Strainer = £99. Overkill for my setup.)

So, as this thread is an a exploratory/discussion thread, I'm going to ask the following:

'What is the correct way/procedure to follow, to choose the appropriate strainer mesh perforation, for any install?'

Shaun suggested that 500 microns would be correct for my situation, with 50 microns only suitable for drinking water.

How can we best choose the correct mesh, for any given usage?

I'd go back to my question "What is the smallest waterway in your system?" and we can probably take it from there.
[automerge]1571732239[/automerge]

Any good? They say low flow resistance and give all the figures for the different sizes. I am not educated in this area of flow through valves/meshes though I have to admit. They do a 350 micron mesh and a 180 micron mesh. The 350 might be ok for your purposes?
 
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Caveat that I'm not a boiler installer, but (and this is unusual coming from me), I do feel you are overthinking the situation.

To be honest, I've never heard of using a line strainer on a domestic heating system, but so long as you check the temperature ratings (I see the BES one will take 110°C) and the pressure drop, which it seems you are doing, I cannot see what harm it could do; as you say, a few old boilers did incorporate a mesh strainer on the return. Usually I use Y strainers on shower pump inlets.

I totally get your point regarding swarf circulating following any work carried out to a heating system. I would also agree that magnetic filters do not tend to catch 100% of the magnetic dirt (hence the Magnacleanse unit has two identical magnets one after the other and some dirt reaches the second magnet even when the quantity is very small). I would comment that the larger bits of copper swarf have a larger surface area and are, therefore, likely to be more mobile. At this point, ANY mesh should be enough to catch it.

What I would say, more critically, is that if you are soldering on a system or fitting a new radiator, then you really should be carrying out a chemical flush using F3/X300 etc to remove oil and flux. If you are flushing using a powerflush pump (and you can hire one for less than £50), you would hope that would kick out any swarf, although I can see that unless you are very careful where you place that pump and how you use it, you might well be forcing the swarf into the boiler.

Dissolved metals resultant from using flux will stop an inhibitor working correctly and if your boiler has an aluminium heat exchanger, then corrosion could be a more serious concern than swarf.

What I would say to answer your question is that the finer the filter, the faster it will clog. In aircon, the air filters are fabric and the dust can actually be forced through the mesh. The solution is to fit a succession of filters from coarse to fine such that the fine filter is never given the burden of the coarse dust. If you were to do that, I can see an argument for stepping down to a very fine final filter, and it would be interesting to see the distribution of various particle sizes.

BES also does a 200 micron filter, but I wonder if the cost/benefit ratio is starting to rise unacceptably?: In-line 'Y' Type Filter - 1" BSP TF 9824 | BES.co.uk
 

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