vaillant ecotec inlet pressure

[Mugwuffin]

Hi all,

This is my first post so hopefully i've put it in the right section. I'm currently working on my gas portfolio before sitting the ACS. Today I serviced ( under Supervision ) a vaillant ecotec plus 831 combi, working pressure at meter was 19.5mb but at boiler only 16mb. I queried this with supervising engineer and he said this was acceptable according to MI, I've looked at vaillant's spec and it says the inlet should be within the 17-25mbar range. Have I been given bad advice or am I interpreting the MI wrong. We had it drummed into us at college that from meter to boiler we could only accept a 1mb drop!! any advice would be great

 

[AWheating]

yes its correct that you are only allowed upto 1mb drop from the meter to the appliance. The problem you have is many new boilers now have high restictions in the gas pipework from its isolation valve to the test point on the gas valve. So many manufactures including vaillant have stated that you may lose upto 1.5mb (may differ slightly from one manufacture to another) in pressure between the isolation valve and the test point. so you could end up with 19mb at the meter, 18 at the iso valve and 16.5 at the test point inside the boiler.

consulting the manufactures instructions and even via phone call is the best way to ensure this is an acceptable reading.

 

[Mugwuffin]

Thanks, will call tech support and see what they say, I didn't want to annoy the supervising engineer at the end of a long day !!! Cheers

 

[AWheating]

ask your engineer to let you see the gas safe technical bulletin that covers this. tb129, tb115 should give you some reading

 

[diamondgas]

Thanks, will call tech support and see what they say, I didn't want to annoy the supervising engineer at the end of a long day !!! Cheers

WP of 16mbar is relatively low and worth querying. End of the day you take into account age of appliance and the whole of the installation before considering any further action. Shutting you up by saying it's okay may have been appropriate depending on the circumstances You are however correct regards the 1mbar drop!

 

[Mugwuffin]

Yep, no one likes being questioned after 4 services and a 15hr day !! the boiler in question was only fitted 10 months ago ? my first thought was undersize pipework ? will see if vaillant can shed some light tomorrow !!

 

[AWheating]

vaillant wont shed any light, they will tell you whats written in the instruction book..... that its acceptable. Its you/the engineer that needs to use experience and training to decide if further investigation is required as regards pipe sizing.

The only comprehensive way to ensure that you only have a 1mb drop to the appliance connection(isolation valve) is to fit a test point in the pipework just before it. Experience is king with situations like this.

 

[diamondgas]

Yep, no one likes being questioned after 4 services and a 15hr day !! the boiler in question was only fitted 10 months ago ? my first thought was undersize pipework ? will see if vaillant can shed some light tomorrow !!

The mi's do state between 17-25mbar at gas valve p1. How they reckon 25mbar is okay is beyond me! I'd be a bit worried there

 

[radswilldo]

As mentioned above, in-built restriction at gas valve. For Vaillants:-

612-630, 824-832(pro,plus,excl),415-428 - MWP 23 = min IP 20
MWP 21 = min IP 18
(min) MWP 19 = min IP 16


637,837,838,937,438 - MWP 23 = min IP 19.5
MWP 21 = min IP 17.5
(min) MWP 19 = min IP 15

All copied from Vaillants Gas Pressure Statement that was e-mailed to me by tech staff. This info did appear in either the 09/10 install manual.

 

[Stuthewarrior]

HI
Did you carry out a time burn on the appliance if so what were your figures?

 

[diamondgas]

As mentioned above, in-built restriction at gas valve. For Vaillants:-

612-630, 824-832(pro,plus,excl),415-428 - MWP 23 = min IP 20
MWP 21 = min IP 18
(min) MWP 19 = min IP 16


637,837,838,937,438 - MWP 23 = min IP 19.5
MWP 21 = min IP 17.5
(min) MWP 19 = min IP 15

All copied from Vaillants Gas Pressure Statement that was e-mailed to me by tech staff. This info did appear in either the 09/10 install manual.

Good to know radswilldo .... Thanks for the heads-up

 

[chris watkins]

Would it not be helpful to Mugwuffin to know from the great minds on here what the consequences of only having 16mbar WP at the appliance would be, to help him make that call, just as the engineer had to? Looking at the MI's is one thing but as you say, having an understanding of the full system is quite another.

 

[diamondgas]

Would it not be helpful to Mugwuffin to know from the great minds on here what the consequences of only having 16mbar WP at the appliance would be, to help him make that call, just as the engineer had to? Looking at the MI's is one thing but as you say, having an understanding of the full system is quite another.

Feel free to enlighten Mugwuffin, chris watkins

 

[AWheating]

HI
Did you carry out a time burn on the appliance if so what were your figures?

time burn?

 

[kay-jay]

time burn?

Got me stumped too. Possibly a gas rate...ie how much burns over time???

Sent from my GT-I9100 using Tapatalk 2

 

[chris watkins]

Feel free to enlighten Mugwuffin, chris watkins

What & spoil all you gas guys fun no you can carry on. Tell him how he might not get the hot water production that the MI,s state for a start.
BTW Mugwuffin may not of heard of a "time burn on the appliance" thought it was normally called a Gas Rate Test on the appliance, is it not diamondgas ??

 

[diamondgas]

What & spoil all you gas guys fun no you can carry on. Tell him how he might not get the hot water production that the MI,s state for a start.
BTW Mugwuffin may not of heard of a "time burn on the appliance" thought it was normally called a Gas Rate Test on the appliance, is it not diamondgas ??

Once has an Isar p1 at 9mbar and gas rate 30kW No issue with the appliance, more with the cooker next to it It's important to have the correct pipe sizing so that the modern boilers don't suck the gas meter down the pipe, figuratively speaking, or starve other appliances!!!

 

[chris watkins]

Once has an Isar p1 at 9mbar and gas rate 30kW No issue with the appliance, more with the cooker next to it It's important to have the correct pipe sizing so that the modern boilers don't suck the gas meter down the pipe, figuratively speaking, or starve other appliances!!!

Thought the zero rated's only only had the very slightest effect on the inlet (0.5 at the most) or was it the type of valve on the Isar's ???

 

[diamondgas]

Thought the zero rated's only only had the very slightest effect on the inlet (0.5 at the most) or was it the type of valve on the Isar's ???

p1 is the inlet, p2 the outlet Chris, I think that's what you're thinking of maybe? You should have zero, thereabouts on p2 on the gas valve! The isar I was testing had been connected to an old 1/2" iron pipe that supplied a cooker as well as the boiler! Had to ID as the burner on the cooker went to a pip on low!!

 

[DirksPlumbing]

The mi's do state between 17-25mbar at gas valve p1. How they reckon 25mbar is okay is beyond me! I'd be a bit worried there

Well keep in mind that Vaillant is not a native manufacturer. In germany when you do your pipe sizing you calculate a pressure gain for every meter of height the pipe is rising. As NG is obviously lighter than air.
Which means every 25m height difference you gain 1 mbar of pressure.

My top reading at a (NG) meter yet is 41mbar. And it was only at first floor .

 

[stevetheplumber]

Well keep in mind that Vaillant is not a native manufacturer. In germany when you do your pipe sizing you calculate a pressure gain for every meter of height the pipe is rising. As NG is obviously lighter than air.
Which means every 25m height difference you gain 1 mbar of pressure.

My top reading at a (NG) meter yet is 41mbar. And it was only at first floor .

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[DirksPlumbing]

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What is your first step when your IP is above 22mbar?

Added: Or unexpected high/low anyway?

 

[AWheating]

What is your first step when your IP is above 22mbar?

Added: Or unexpected high/low anyway?

check your water level

 

[DirksPlumbing]

check your water level

Never! I instantly tell the customer the truth about the installer oversizing the pipe and causing that way a high IP .