3 tee rule anyone?

[keith1967]

hi all, what is the 3 tee rule?

 

[REDSAW]

mines one sugar!

 

[Mike Jackson]

It's the order in which the bypass, cylinder return and heating return are connected. Running from the boiler back the connection order should be bypass, cylinder, heating. After the heating return the cylinder return and bypass should be teed in at right angles to prevent reverse circulation. It's a very simple rule but it's amazing how many people ignore it and then can't work out why the upstairs rads are hot in the summer.

Mike

 

[Jamino92]

It's the order in which the bypass, cylinder return and heating return are connected. Running from the boiler back the connection order should be bypass, cylinder, heating. After the heating return the cylinder return and bypass should be teed in at right angles to prevent reverse circulation. It's a very simple rule but it's amazing how many people ignore it and then can't work out why the upstairs rads are hot in the summer.

Mike

Couldn't remember the order aha so cheers! Need this for today!

 

[dontknowitall]

I'll have another study upstairs - I reckon I've got this problem and have never pin pointed it.

 

[kirkgas]

It's the order in which the bypass, cylinder return and heating return are connected. Running from the boiler back the connection order should be bypass, cylinder, heating. After the heating return the cylinder return and bypass should be teed in at right angles to prevent reverse circulation. It's a very simple rule but it's amazing how many people ignore it and then can't work out why the upstairs rads are hot in the summer.

Mike

one of my "3T's" is the vent pipe right off the boiler flow, then the cold feed, then the hot water return is the last T before the return pipe goes back to the boiler

 

[BLOD]

Blimey ! Including redsaws that makes it the 7 T rule ?

 

[REDSAW]

any hobnobs?

 

[fuzzy]

first t on flow should be cylinder, last on return should be cylinder, if not you can get reverse circulation

 

[Halesowen1]

Known as the Common Tee.
The return from the cylinder to the boiler should be the last Tee, in other words return all the heating in before the cylinder. The further away the better to stop the chances of rads heating up when hot water only is on.

 

[Unregistered]

Can someone draw a diagram of the 3 tee rule. I am studying plumbing n heating in my 2nd year.

 

[Best]

Can someone draw a diagram of the 3 tee rule. I am studying plumbing n heating in my 2nd year.

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[Inverness]

Hi to the pros of the plumbing and heating department.my friends dad's house is a sealed s plan system. When i call for hot water some rads heat up. I've replaced the motorised valves to honey well.. It's always been like this since they can remember. With out looking under the floor to further investigate. Is there anything I could do above the floor to give some clue to why this is happening.. I am in my second year apprenticeship.

 

[Inverness]

Can someone give a diagram on a -s-plan the first tee is the heating zone valve or the hot water zone valve? Can so one give a diagram the way it should be done.

 

[Best]

I will try to explain it, but might be hard to say. You normally do the S plan system with flow solely coming from boiler and then to a point where you tee off (2 branches) with 2 motorised valves. One for heating and the other for rads and then pipe to those.
The return to boiler is the key to this. The Return goes from the cylinder back to the boiler. You MUST only branch off this main return once! Ideally at boiler, (but it can also be done differently & I will explain that later). If you branched off with a second tee as you passed a rad return valve (very tempting), you will create a loop in the return circuit through the rads.

(Different method of using a return tee off for cylinder, ie - return branched to rads first, cylinder return continuing further, will work providing the rad return branched pipe is dipped down from its tee to prevent gravity heat to rads as pumped return passes- but this is usually not the way to do it)

 

[Best]

Figure 9 might help you
http://heating.danfoss.co.uk/PCMPDF/Introducing Controls.pdf

 

[Masood]

Can someone draw a diagram of the 3 tee rule. I am studying plumbing n heating in my 2nd year.

It's in your text book!

 

[sheff paul]

It's the order in which the bypass, cylinder return and heating return are connected. Running from the boiler back the connection order should be bypass, cylinder, heating. After the heating return the cylinder return and bypass should be teed in at right angles to prevent reverse circulation. It's a very simple rule but it's amazing how many people ignore it and then can't work out why the upstairs rads are hot in the summer.

Mike

Never took bypass back to boiler,its always linked to the cylinder return ,which is then took back to boiler ,always left at least a metre plus space between cyl, return before tee'ing rads into the return pipe.Done over 600 's plans', never had any rads warm when HW is on..

 

[Billy Bob Bob]

bloody hell,holy thread revival ,i dont get why many struggle and its not the last 3 t rule,get the facts and terminology right its easy Last tee must go back to domestics or as tam would say for the hard of thinking,the last tee on the return must be the return from the cylinder,no rads too come off after this t