vent pipe run

[chrishutt]

Yes it will pump over guaranteed.

No it won't. As ChrisR explained with his diagram (albeit with minor errors), the resistance of the pipe between the vent pipe and the feed pipe connections is so low there would be very little positive pressure at the vent connection compared to the neutral point of the feed connection.

Again referring to ChrisR's diagram, he shows that the pump head does not manifest itself only on the outlet side of the pump, or even in equal measures on both outlet and inlet sides (as I initially thought), but will manifest itself in relation to the relative resistances of each route from pump to neutral point (feed connection).

In the case of the faulty Viessmann drawing, the pump head would manifest itself mostly as a negative pressure on the inlet side, extending around the system back to the neutral point.

 

[Softus]

Yes it will pump over guaranteed.

It isn't guaranteed at all - the water will take the path of least resistance, so if the 'back pressure' in the pumped primary circuit is lower than the head of water in the F&E, then the system won't pump over.

Having said that, if the inertia of the water primary circuit is too great, then there might be a spurt of water from the vent when the pump first starts.

 

[doitall]

Time you two went back and had another look at the drawing

Check out the by-pass on the S plan, and the divertor valve on the Y plan.

There's a hundred quid to a charity of your choice say it pumps over, if you want to knock up a model.

I got a pump and a few second hand valves if you want me to drop em over Chris

Incidentally the Op has an combined cold feed/vent

 

[corgiman]

so building regs say flue has to be 2.5mtr from facing boundary.

No they don't. It's a lot more complicated than that.

1. The Building Regulations (Part J) themselves will only set out a general requirement, like Combustion appliances shall have adequate provision for the discharge of products of combustion to outside air (not sure of exact wording). This is a legal obligation.

2. The Approved Document J (ADJ) will give Guidance on how that legal requirement might be met (in this case the Guidance figure is 600mm to boundaries). You don't have to follow the Guidance but if you use an alternative approach to meeting the requirements of Part J you must be able to demonstrate that it does so. Following Manufacturers Instructions would be a way of doing this.

3. British Standard 5440-1 Also gives guidance on flue terminal clearances along the same lines as ADJ. Following the guidance in British Standards is another way of meeting the legal requirements of the Building Regulations.

4. Terminal positions are also covered by the Gas Safety (installation & Use) Regulations 1998. For example Regulation 27(5) says "No person shall install a flue other than in a safe position". Gas Safety Regulations are a legal obligation that cannot be over-ruled by other considerations.

5. The situation is further complicated by the figure of 2.5 metres given in the Guide to Condensing Boiler Installation Assessment Procedure. This figure (2.5 metres) is only given for assessment purposes.

and to add confusion the CORGI book says it should be at least 1.2 mtrs

Does anyone have a definative answer to the cock up which is the building regs??????????

 

[Softus]

I got a pump and a few second hand valves if you want me to drop em over Chris

Surely you have got to be kidding - AFAIK you haven't done that experiment about the unbalanced mixer valve topic yet!

 

[chrishutt]

I got a pump and a few second hand valves if you want me to drop em over Chris

I've got plenty of plumbing junk cluttering up my flat as it is, but thanks for the offer. I was thinking of knocking up a test circuit, but I don't honestly think I'll get round to it in a hurry - too many neglected tasks to catch up with.

Check out the by-pass on the S plan, and the divertor valve on the Y plan.

I see that they've connected to the diverter valve wrongly, but what by-pass? Are you saying there should be one but isn't? Only if the heating circuit was all TRV surely?

 

[doitall]

Got to have an by-pass after the pump on an S plan, when the boiler has an over-run.

 

[chrishutt]

Ah yes, I'd forgotten about the pump overrun. Thanks for reminding me.

 

[doitall]

I got a pump and a few second hand valves if you want me to drop em over Chris

Surely you have got to be kidding - AFAIK you haven't done that experiment about the unbalanced mixer valve topic yet!

Why would I want to do an experiment, I've seen more valves and taps backing up than you've had hot dinners.

I know what the symptoms are, how to trace the problem with the minimum effort, and how to cure the problem.

I do not need to play with the toys, or humour anyone that happens to disagree.

Who knows in years to come you may remember what thescruff said

 

[bripl]

feeling modest tonight dia?

 

[doitall]

feeling modest tonight dia?

Maybe later bripl is modest the Irish nymphamaniac.

 

[Softus]

Why would I want to do an experiment

Er, because of this:
//www.diynot.com/forums/viewtopic.php?p=389748&highlight=#389748

I've seen more valves and taps backing up than you've had hot dinners.

Maybe you have, maybe you haven't. Either way it's not a very impressive claim.

I know what the symptoms are, how to trace the problem with the minimum effort, and how to cure the problem.

Apparently not.

I do not need to play with the toys, or humour anyone that happens to disagree.

Then I have no idea why you're posting on this topic, given that some people disagree with you.

Who knows in years to come you may remember what thescruff said

Well I know, and I know that I won't.

 

[doitall]

As I said complete rubbish.

I suggest you take the issue up with the manufacturer, because they have it wrong.

Then I have no idea why you're posting on this topic, given that some people disagree with you.

Thats their choice softus they don't have to agree any more than I do.

Perhaps you should read the Viessmann book as well, it's very educational in how not to install a boiler.

 

[Softus]

As I said complete rubbish.

I suggest you take the issue up with the manufacturer, because they have it wrong.

Then I have no idea why you're posting on this topic, given that some people disagree with you.

FFS. This is nothing like the sequence of posts. It actually went like this:

I do not need to play with the toys, or humour anyone that happens to disagree.

Then I have no idea why you're posting on this topic, given that some people disagree with you.

Perhaps you should read the Viessmann book as well, it's very educational in how not to install a boiler.

No need - I don't install boilers, I just diagnose faults introduced by installers. The kind of people who, for example, don't understand how mains pressure forces hot water out of a cylinder cold feed and up into the CCS, and who are too closed-minded to conduct an experiment.

 

[doitall]

Perhaps you should read the Viessmann book as well, it's very educational in how not to install a boiler.

No need - I don't install boilers, I just diagnose faults introduced by installers. The kind of people who, for example, don't understand how mains pressure forces hot water out of a cylinder cold feed and up into the CCS, and who are too closed-minded to conduct an experiment.

As i said you only have to bridge the mains cold with the hot and even you will see where the water comes out