Favoured F&E PIPEWORK LAYOUT

[mutley racers]

I have just read the post on this old skool ex plumber trying to repair his heating system from pumping over. So I was wondering, does everyone have their own safe method?

Example: Close coupled on flow behind the pump, Anyone use air seperator? H, plan. Which i have heard of but not sure what the layout is. Or even the feed teeing into the flow coming straight out of the boiler.

Are there any that are full proof no matter what the situation? I.E How much head from f.e. to boiler?

Do you stick to the same method all the time?

Interesting

 

[ecowarm]

Different ways, mostly vent, feed and then pump, tee's as close as you can get.
Different for solid fuel and link up systems.

 

[tamz]

There are many ways of doing it that can all be correct depending on the system.
New systems i'd do a close proximity (teed within 150mm) on the flow before the pump. Low head possibly with an inverted feed or maybe a feed expansion or maybe an aerjec. Depends how i feel or what i think would be best
All depends on the system and the set up. Boiler swaps are different again. You just need an understanding of the relationship between the positions and the pump and how much resistance through the boiler etc.
There is more than one way to skin a rabbit.

 

[mutley racers]

Never heard of the inverted tee. How does that go? Also, the feed and expansion, is that just teeing the cold feed into the vent pipe? Whats an aarjec?? A couple there i have never heard off. Wow, You can tell am a youngster hey. And at 33

 

[Mike Jackson]

myson aerjec - Google Search

Normally close coupled or combined feed and vent for low head systems for me.

 

[bob the plumber]

you cant beat your 150mm expansion feed behind pump, never goes wrong unlike the hundreds of combined feed expansions ive been to

 

[mutley racers]

oh i see, the air seperator. I have heard they clog quite easily, is it true? Also, do you think the close coupled system works with the tank 1 metre above the pump? Or will it suck in air

 

[ecowarm]

Air seperator more like sludge trap

 

[tamz]

oh i see, the air seperator. I have heard they clog quite easily, is it true? Also, do you think the close coupled system works with the tank 1 metre above the pump? Or will it suck in air

It will work ok. if you can get the vent to rise about 500mm above the tank. If you cant get the headroom then a feed expansion (combined) will be better.
Aerjecs do tend to gather any muck. They work by slowing the velocity of the water as it passes. You can make something that will do the same job from a bit 1 1/4" and a tee extractor.

 

[mutley racers]

ok cool thanks tamz. Also, what is this inverted feed?

 

[tamz]

Same as a close coupled but the tee for the feed points down, drops about 6" then rises.

 

[mutley racers]

so what about the 3 T's rule? From boiler flow: vent, cylinder, rads
From boiler return: feed, cylinder and rads

 

[mutley racers]

ah i see, so it forces the air out then?

 

[Nostrum]

No, it creates a neutral pressure 'zone' so that there is neither positive or negative pressure being applied that area (the air seperator/aerjec)

 

[mutley racers]

wow, loving all these posts. Thanks chaps. Its much appreciated.

 

[Nostrum]

Basically the vent comes off the top, air being lighter than water will rise to the top of the chamber (the aerjec) and find it's way out via the expansion. Thats the reason they collect crud, because the neutral spot allows the particules to 'drop' and form a sediment in the bottom of the aerjec. At the same time because it's a neutral spot there is no chance of pumping over.

The original spirovent dirt seperators work in a similar way (before magnets were introduced) in that a neutral spot was created and the sediment dropped into the conical shape and stayed there until it was drained out.

 

[tamz]

Don't know what the 3 T's rule is.
The flow is immaterial where anything tees off. Just make sure the vent is before the pump.
Same with the return, the hw tees in nearest the boiler.

Where the feed enters the system is the neutral point. From there to the pump is under suction and from the pump to the feed is positive pressure. Do a wee sketch and put + and - signs on it to see what happens with the feed and vent in different positions.

The reason a close coupled has to have the tees within 150mm of the feed is to keep it close to the neutral point. If it was outside that space it would probably pump over unless the vent was really high. The wider the space the more chance of it doing so.

 

[tamz]

Vent pipes should also come off a horizontal section of pipe where possible. Helps get rid of air better as air runs along the top of the pipe.

 

[mutley racers]

thanks tamz. That is the first i have heard the horizontal part. I do have all the diagrams on positive and negative pressure. Do most people these days install system boilers if the house is in need of a new one. Or, as it is cheaper to repair parts externally, buy normal open vent but put all safety controls external? Which are cheaper to replace and easier?

 

[bob the plumber]

the boss rectified a system a few months back. he put the exp and feed in behind pump but with a wider gap over the 150mm, it pumped over, after doing it again within the 150mm it worked fine, quite sensitive!

 

[tamz]

System boiler take the thinking out of heating. You just stick it in and it works. Regular boilers need a bit thought and care as to the pipe layout regarding the feed and vent but are cheaper to buy than system boilers. If the existing system is functioning well enough there is no reason to change it for a system boiler.

 

[PlumbBobBob]

thats why you always come off the top of a hwc with a min 450mm horizontal pipe run before you have vent/feed, to get rid of any air in the water.

 

[mutley racers]

ah ha, that,s what i thought. The plumbing has been taken away with the system boiler. But steve, what if you have not got a horizontal run off the flow in an airing cupboard? Say the flow comes kitchen and up into loft and down into airing cupboard. So all a vertical run

 

[PlumbBobBob]

then i would think an auto air vent would come into play at the highest point

 

[tamz]

Tee your vent off in the loft and it will do its job. The return would need an aav.