Vaillant VCW221 Problem - time/delay cycle on CH

[mcaroon]

What is the time delay between burner (on/off) when the CH is ON, at the moment my boiler is set to dial 5 and the timing is 5mins burner ON and 9mins OFF (delay), is this normal?
For some reason the timing/delay screw has been adjusted recently by the engineer, and i feel that time/delay between cycle is excessive.I have contacted him and he suggested adjusting the screw till desired settings.

What should normal time/delay cycle be?
How to i reset to factory default setting?

Thanks in advance for advice/comments.

 

[Agile]

The boiler stays ON until the set flow temperature is reached.

It then stays OFF until the flow temperature falls to the boiler's hysteresis "on" temperature is reached, that's usually 2-5 degrees below the set flow temperature.

There is a minimum OFF period which can be set on some boilers and is fixed on others. It is called the "anti cycle delay". They typical figure used is three minutes.

Its most likely in your case than the flow temperature is not falling fast enough to cause the boiler to relight.

Tony

 

[mcaroon]

thanks agile,
like said the time/delay has been tamperd with so how do i reset?

 

[Agile]

The anti cycle delay is settable with the slotted adjustment just above and to the right of the green light on the diecast control circuit box.

Its adjustable from 1 min to 12 min with a factory default of 5 min.

BUT I don't expect that it is set at 9 min for the reasons I explained earlier!

Tony

 

[mcaroon]

tony, prior to engineer tampering with the timing screw it was ok.

so what do you suggest i do to correct this situation?

 

[Agile]

It may not need changing at all.

You will probably be able to measure what it currently is by:-

Turn on heating for five min from cold. Turn boiler temp down until boiler goes off.

Start timing!

Turn boiler temp up to max and see how long it takes to come back on again.

Or just set adjustment to about the middle of the setting.

Tony

 

[mcaroon]

Thanks Tony,will try that later, but are you suggesting there is nothing wrong with the setting as is (5min on and 9 off) as my first post.

Anyway how do i reset the screw to factory setting 5min?

 

[Agile]

What I mean is that the 9 min off may not all be due to the anticycle setting but waiting for the returning water to match the set restart temperature.

Tony

 

[mcaroon]

Tony,i have inherited another problem, the pressure drops to 0 after when CH is off.The overflow drips only a drop when the pressure reaches 2.5-3bar.

How/where/what can i check what is at fault( ie PRV,EV, boiler pressure)?

Thanks in advance

 

[Agile]

Please read the FAQ all about the EXV!

Tony

 

[mcaroon]

Where is the FAQ located and sorry for the new thread started earlier.

Thanks

 

[Agile]

Click on "Plumbing and Heating and you get a list of topics!

One is FAQ.

For reasons that I don't understand there is also a similar one headed Wicki too.

Tony

 

[denso13]

//www.diynot.com/wiki/plumbing:faq:faq7

 

[mcaroon]

Thanks guys, will check it Pressure Vessle and could it be PRV at fault and how do i check?

 

[Agile]

It will be the EXV at fault!

But the constant leaking from the PRV may have caused it to leak.

After you have solved the EXV then click the PRV six times and it will probably stop dripping ( if it does ).

Even when they drip they usually stop after a few days!

Tony