Y Strainer - Technical

[SirLancelot]

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 and/or CH return loop:

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Credits: i) Choosing the Right Straining Element, Part One - The Pipeline Flow
ii) Caleffi Hydronic Solutions


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 (frequency 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 gauze/strainer.

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 should the strainer/gauze get 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.

 

[SirLancelot]

The reason I've brought this topic up is I have 25 year old pipes, with a ten year old system filter & a relatively new ecotec 837 boiler.

There is no filter on the inlet/return manifold - like you used to get with the performa boilers:

https://www.diynot.com/diy/threads/...-central-heating-filters.449825/#post-3543065

My question is that to protect the boiler - if some manufacturers do include a strainer from factory - why do others no do this?

I'm hoping others are willing to explore this topic.

P.s The images were found on google - I just took some effort in putting the post together - so that it's as info rich as possible.

 

[SirLancelot]

Yes this thread is more than two years old. But - it has value still.

Given that technology has moved on - new system filter designs are reaching the market - specifically to deal with NON-magnetic debris in very old systems.

I noticed adey have added a collar to the magnacleans - to trap non mag debris. A newer company has created the trappex system filter, which claims to address non mag debris too.

What are members thoughts on approaches to actively dealing with non-magnetic debris?

 

[transam]

There are magnetic filters that also have an in built gauze or filter for non magnetic debris ?

 

[SirLancelot]

I have the origional adey 'twintech', (magnetic + guaze filtration). However it was royally slated for leaking & other aspects of its design.

I'm trying to find a solution for effective filtering, of non magnetic debris from a CH system.

Surely there are solutions out there?

 

[Madrab]

Most, if not all, of the mainstream filters are designed to slow the flow through the filter allowing any significant non ferrous particles to drop out of the flow and collect at the bottom of the filter. Any non ferrous particles that miss that filtration system, I would suggest, wouldn't be large enough to cause any issues to the boiler.

I believe that a mesh filter could cause major flow problems very quickly if debris was caught and blocked the filter in a dirty system. That could cause significant damage to the boiler. An auto bypass would probably be needed as part of the design.

I don't believe that adding another choke point into a system that could be easily compromised would be worthwhile. All that is required is that the system is designed properly, is clean, conditioned properly and serviced regularly. If that was done correctly and looked after even a magnetic filter shouldn't even be needed.

 

[SirLancelot]

Your points make perfect sense.

I would like help understanding a couple of things:

A) When the filter in the y-strainer gets blocked, naturally it will restrict the flow. My question is - Do combi-boilers have safety mechanisms in place, to shut off in such cases for CH flow?

(Recently. My plate heat exchanger got blocked from system debris - and the boiler shut itself off).

B) Other than power flushing (not good for old joints or certain scenarios) can anyone suggest another way of getting rid of non-mag contamination in a sealed CH system?

C) I hear you about the cyclonic action of certain filters - but for a cyclone system to work properly - sizing and flow rates need to be adjusted (i'd imagine) for it to work properly. Which filters do this well?

 

[Madrab]

A) When the filter in the y-strainer gets blocked, naturally it will restrict the flow. My question is - Do combi-boilers have safety mechanisms in place, to shut off in such cases for CH flow?

Overheat stat. When the flow is reduced the boiler cant get rid of the heat quickly enough, boiler overheats and shuts down - not ideal to have a boiler constantly overheating and shutting down until the flow cools or a filter is cleaned.

B) Other than power flushing (not good for old joints or certain scenarios) can anyone suggest another way of getting rid of non-mag contamination in a sealed CH system?

Powerflushing is a 'last resort' in my opinion. The best offense is a good defense, the boiler should never be allowed to get to the point where powerflushing is required. Good design, servicing and maintenance is needed, sadly this is not a priority for a lot of people. I'm workign on one just now that has a host of issues due to the system being filthy. The boiler itself needs several parts and work on it as it's just got badly clogged up, that and it needs another part, that's not relevant to the system condition but as it wasn't registered nor been serviced yearly then the warranty is void, so it is going to cost the client hundreds to put it right.

C) I hear you about the cyclonic action of certain filters - but for a cyclone system to work properly - sizing and flow rates need to be adjusted (i'd imagine) for it to work properly. Which filters do this well?

Without getting into actual design and performance figures of ever filter it would be hard to suggest which ones would be better than other, it really comes down to real world 'which ones works well for a certain individual'. I believe the design of the inlets/body and outlets of most filters these days are such that there is sufficient slowdown/eddies etc to allow particles to drop out of the flow and captured within an area outside of that flow (so it's not picked back up and re-introduced), regardless of actual system flowrates. Of course it won't capture everything but without a fine mesh filter that would be extremely difficult to do but that would then bring it all back to that start with the potential for constantly clogging mesh filters.

 

[transam]

The reason I've brought this topic up is I have 25 year old pipes, with a ten year old system filter & a relatively new ecotec 837 boiler.

There is no filter on the inlet/return manifold - like you used to get with the performa boilers:

https://www.diynot.com/diy/threads/...-central-heating-filters.449825/#post-3543065

My question is that to protect the boiler - if some manufacturers do include a strainer from factory - why do others no do this?

I'm hoping others are willing to explore this topic.

P.s The images were found on google - I just took some effort in putting the post together - so that it's as info rich as possible.

no particular reason (assuming there is room) why you cannot put 2 magnetic filter in line if you wanted to

done it on a few systems in the past

y strainers if installed going up into a boiler should have the arrow of flow direction in reverse arrow opposite to flow direction

probably ?? technically ?? the most efficient filter is or was the cheap and cheerful (tacky) in line filter from adey / euro spares

nothing but clean water will get through that , and that is probably the problem with them , easily blocked and can cause chaos

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• transam
• 5 Aug 2011
• 4

blocked plate exc black heating side blockage and white is the hot water side restriction


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• transam
• 16 Apr 2015
• 1

and two interesting filter installs one is a magna leak and the ceiling one is the dire original fernox F1 filter