Setting Honeywell DU145 Auto Bypass Valve

[antsals]

Good afternoon,
I'd appreciate a quick bit of help.

I had new hot water tank, central heating pump, controls etc. installed last Nov; I kept original boiler for now.

I did a lot of research into the products I wanted in my system; found a good plumber through people I know that have had work done. (I'm an engineer by trade and have read up on every product possible, but trying to learn on how systems should be set to get optimum)

I moved and installed new rad on Thursday re-filled system fired it up.....happy days not leaks......but it took ages for "hot" water to reach that rad. Also I had noticed a problem that a rad in utility (I would say it was end of the line) didn't even get hot. I was unsure if it was since the upgrade of CH or always been like that cause we have only been in the house for a year.

Did balancing of the system and realised that a rad one up the line from the rad that got no heat was fully open both TRV and lock shield side. Tweaked that and heat from the cold rad.

In the meantime I have realised that as soon as the hot water starts pumping it goes down the bypass straight away. Reading Honeywell’s tech docs it guides to say that this is a safety device and should be active when flow is required to the boiler / pressure increase because of TRV close.

The plumber has left the autopass set below 1 at the lowest point. I assume this cannot be correct, I have followed the guides from Honeywell and I have calculated at between 3 - 4? Could this be correct? Would this push more heat through the rads??

I have an Ideal FF360 Classic boiler, Grundfos Alpha 2 15-60 130 central heating pump.

I'd appreciate some guidance.

Cheers
Ant

 

[happyflyer]

The more the auto bypass is screwed down the more water goes through the system the less goes through the bypass, adjust it a bit at at time, Ant

 

[tamz]

When the system is operating normally the bypass should be closed. It is there to provide a route for the water to flow through as the system becomes satisfied and shuts down.
It just takes a bit of time to set it correctly but at 1 it will be open constantly and providing a short circuit.

 

[happyflyer]

I don't know how anyone can really set up a auto bypass valve its a bit rule of thumb without the thumb, the boiler will need a flow through it when thermo rad valves close down or inline zone valves, it is really impossible to know how much water is going through the system and how much through the bypass loop. There are a number of products on the market use mainly commercially that will indicate how much water is travelling through a pipe, they have a glass window with a spring load wedge that moves along a scale the more water going through the more the wedge moves up the scale, I doubt anyone ever fitting one when the plumber has a thumb. I agree 1 will let a hell of a lot of water back into the boiler starving the rads of water.

PS looks like the 146 has a meter built in has anyone used it, too expensive at £50.00

 

[tamz]

Never seen let alone used it Happy (btw whats your name?).
Nothing much wrong with my thumbs apart from the odd twinge of arthritis :smile:

 

[happyflyer]

Never seen let alone used it Happy (btw whats your name?).
Nothing much wrong with my thumbs apart from the odd twinge of arthritis :smile:

Tony Tamz,

They are made by a company call taco-therm, back in a min


Tony

PS you will still need this and the ABV this just tell you how much water is going through the ABV, get them in different ranges zero to about 1 l/s will do for boiler up to 30 kw this one goes up to 2.4 ls that would do a 100kw boiler big boys time Tamz

 

[tamz]

Pleased to meet you Tony.
Tam

 

[antsals]

So is a bit of suck it and see......what would you suggest setting the auto-bypass too? 3 as a starter? How will i know if its doing what it should? If everything is cold boiler fires up and it goes straight through auto bypass tweak it upo again?

Thanks for replies!

Ant

 

[tamz]

Screw it down fully to start with and as the system is closing down (you close it) open it up and feel it.
As said it is a bit hit or miss and guess work but not hard to do.

 

[antsals]

Screw it down fully to start with and as the system is closing down (you close it) open it up and feel it.
As said it is a bit hit or miss and guess work but not hard to do.

So screw it down so the number is high.....so nothing goes through the bypass.....then shut down the requirement so central heating pump goes off and as it does open the bypass until i feel som heat / flow through the pipe. DO i then leave it at that or just tweak it down a touch so to put a little resistance on it?

Ant

 

[SafeGasInstall]

run system and when hot enough then turn cylinder stat and then root stat down so motorised valeves are closing but pump over run will run and then start loosing the auto bypass and you will then realised when water starts to flow through it , once done must re run hw and ch to make sure when under normal operation water does not go through the auto by pass

in order this to work you must have wired the sl to the boiler to have pump over run

 

[SafeGasInstall]

I am stan tony , and you are good contribution to the forum Happy

 

[antsals]

run system and when hot enough then turn cylinder stat and then root stat down so motorised valeves are closing but pump over run will run and then start loosing the auto bypass and you will then realised when water starts to flow through it , once done must re run hw and ch to make sure when under normal operation water does not go through the auto by pass

in order this to work you must have wired the sl to the boiler to have pump over run

Thanks for that, I will give it a go.

Ant

 

[SafeGasInstall]

start from fully closed auto by pass , its easy tbh after you have done few

 

[chris watkins]

Hi
What setting have you put the Alpha 2 on, is on auto adapt ?

 

[antsals]

Hi Tony
What setting have you put the Alpha 2 on, is on auto adapt ?

Yep it's set to auto adapt. Is that ok?

Ant

 

[SafeGasInstall]

I did not realise there was a alpha 2 !
Chris does alpha 2 need a auto bypass to clear the heat exchanger from the hot water ? I think if its on auto adapt autobypass will not work!?

 

[antsals]

Oh right......I realised it adapted its speed you can set it to pressure also to keep it constant.

Bypass seems to work in auto adapt cause it was working when it was set to the lowest setting. Even if it was set at 1 still bypasses.

Ant

 

[tamz]

I'm sorry. I never noticed you had an alpha 2.
An automatic bypass is not really suitable on this as the pump would need to be set to constant pressure which kind of defeats the purpose of the alpha pump.
It should really have a manual valve and a flow gauge. The flow should be set to around 2.5litres/minute through the bypass.
You will find guidance on the grundfos website of how you should tackle this.

 

[happyflyer]

I think you have all got you own ideas, this is my take, close the ABV completely by screwing it fully down so the spring in compressed, now its like you have no ABV in the circuit or at least the pressure require to lift it off its seat and let water go around the bypass will be pretty high.

Now fully balance your system with every thing fully open all stats wound to the top, don't let anything shut you down during balancing, take off all TRV heads, BTW this is what I do know for work, I witness engineers commissioning commercial system, they are more tricky than domestic.

I had 10 plumbers working for me when I was 22 until 32 (69 now) and I install 1000 s of domestic systems, tell you all about that some other time, started with solid fuel, then oil and then when North Sea Gas came a shore it all went gas, are you all asleep yet children.

I would not let any of my men balance a system, when they had filled there systems, I would leave the system I was installing and go and balance theirs, I now know why plumbers can't balance domestic systems, I didn't tell them how to do it, and they could never pass it on.

A lot of plumber don't understand how a 15 mm LS valve works, you need to sit down for five minutes with a cuppa and a 15 mm LS valve and fondle and caress it like a blond, you need to know how it works, you see it's not a balancing valve at all, its a shut off valve for a painter and decorator, it's sole purpose is to drain the radiator.

Now it just happens that if you designed a system correctly you would not need to balancing it, and I could still do it based on a standard pressure drop or standard water flow, but this is not going to happen and so we use the LS valve to help us put right the long runs pipe to one circuit and the short runs in another and we hope that pump is big enough the force it around, if its not we can get a BIGGA one, oh yes you have all done it, down the merchants "PETE HAVE YOU GOT A HIGH HEAD PUMP" Peter say "HOW HIGH" well how high have you got. Most pump off the shelf now are pretty high now because pipe sizes have gone small, the old BSA Opio pumps I fitted when I was a lad wouldn't pump enough water of give enough head to supply 2 rads on 22mm F/R 20 ft long???

So, back to the LS isolating valve, got your cuppa, sit down send your Doris in the other room and now we can play with it, don't tell her what your at.
Get our spanner, adjustable, please not pliers you wont get the feel of it, never balance with pliers, now close the valve fully you can't blow down it shut, now when you blow down it, as we adjust it take off the nut and olive off the tube end, now open the valve HALF A TURN and blow NOW ANOTHER HALF TURN and blow and NOW ANOTHER HALF TURN when the LS is two turns open you should notice that there is very little difference to it fully open which might be 4 turns, depends what the valve make is, they are all crap the motion of the seat is not linear.

So what have we proved, the control of a 15 mm LS is not what you thought, when you turn a LS down by one turn its possible still taking as much was as it is when it's fully open, perhaps you all new this and I have wasted my time, anyway you could pass it on to those who are not so sure, like I didn't, look in the mirror lads you have a round grease mark and your lips bleeding where you cut it on the chrome off that LS valve, just check it before you blow, the chrome not water it use to be.

On a commercial system we only use line valve which have a linear action 50% open means 50% open these valves start at 15 mm up to 150 mm and bigger, we still use the lovable LS valve for rads, still crap, however when commissioning inline valve we use a flow meter the valve has two test cocks, so we cant go wrong, it gets us to a point where we know how much water is going into a zone of rads and we are back to the spanner on the LS.

What I will say is this is you skimp on your pipe size you will struggle with balancing, install long runs you will struggle, mini bore system are slightly different but you can't use long runs of 10 mm tube you need to keep the manifold close to the rads, mini bore systems now are not true mini-bore they don't know what the hell they are, plumbers just use 22 mm tees with 22 mm x 10 mm reducers where ever they want a branch, hybrid.

Hope this as help

Tony

 

[happyflyer]

Oh I forgot, the 15 mm and 22 mm gate valve are exactly the same, crap for balancing two turns open and they are fully open.

One other very important point on domestic, the coil in the cylinder if you have one offers the lowest resistance to flow of any other part of the system, therefore when you balance the system on a 3 port valve with the ball in the middle you must go and balance the coil along with the rads, I would start with the 15 mm balancing valve off the coil 1.5 turns open and work up from that.

I you struggle to get a 10 Deg C drop across your rads then you have stretched you pipe sizes to the limit or you have got silly long runs that are using up the head of the pump.

And remember this, you use a high head pump it cost more to run than a normal pump, if you have the speed set up to 3 then the life time running cost is high, I remember when all system were all gravity, Doh, just about and two pipe system just invented.

Tony

 

[happyflyer]

I am stan tony , and you are good contribution to the forum Happy

Thanks Stan I hope I can make a reasonable contribution, looks like a good set of lads and I like a bit of a laugh, please don't take me too serious my gran said I should have been on the stage.

 

[SafeGasInstall]

Tony do you have a link to a domestic flow regulator ! As I thinking to start fitting some along with the abv ! I also have noticed on few systems where abv is letting by when it shouldn't ( under normal operation on one of them systems where the pipe runs are long and systems are overloaded with bigger rads and where boilers work on max as this is only when customer think there heating is running ok

 

[happyflyer]

Tiny do you have a link to a domestic flow regulator ! As I thinking to start fitting some along with the abv ! I also have noticed on few systems where abv is letting by when it shouldn't ( under normal operation on one of them systems where the pipe runs are long and systems are overloaded with bigger rads and where boilers work on max as this is only when customer think there heating is running ok

I will have a look and see if I can source a lost cost on for you


Tony I am Tiny all the same 5.4" I could get in place that big plumber couldn't it was a pain really I got all the crappy jobs

 

[happyflyer]

Here it is take a look and i will see what the best price is Monday, if you fit one of these you will see the flow
change in the viewing window


http://www.taconova.com/fileadmin/u...a/downloads/DB/HA/TacoSetter_Inline_100_e.pdf


Tiny Tony