Valliant 418 circulation problem

[boilergp]

i've installed a valliant 418 open vented, in a big house with 12 radiators, it is giving me problems, both with the heating and hot water, most of the radiators only get warm and not hot, and water is only only enough for two people's shower, ( or so i been told by the owner ). i ve tried balancing all the radiators it worked, but the next day same problem came back. when i check the flow pipe on all the radiators it is hot enough and there is no air in the system, thats been takin care of already. i am not sure if this boiler is big enough for such BIG HOUSE.
Can someone please HELP.

 

[DP]

Are you a registered gas installer? Does not appear so from the tone of the post.

 

[boilergp]

I am not registered yet but i am working with a gas safe registered Engineer and both of us are trying to solve this problem together, i came across this brilliant website, so thought someone might be able to help us.

 

[picasso]

How big is a big house ?

 

[boilergp]

House has 4 bedrooms, two bathrooms and two receptions. the boiler is installed in the garage. System has 6 600 x 1600 double radiators, two 600 x 1600 single radiators and 4 small radiators, the storage tank is 120 Ltr approx , and both water and heating are fed by two water tanks in the loft. system also has two diverter valves one for hot water and the other one for heating.
Their old boiler was faulty, so the system didnt work for good two months.
they were using the hot water storage tank electric immersion heater for water.

 

[Beerlover]

Can you access the D codes?

If so can you tell me the readings form D.40 & D.41?

The readings must have a difference of more than 25 degrees, otherwise the boiler will hold on low gas. The S code S.53 will be shown.

If I'm being too techinical I'll try and explain a little more

 

[picasso]

If the hot water cylinder is 120ltrs then its too small for the property, 18 kw might be enough for the heating but it wont heat the cylinder and all the rads at the same time, the boiler might be just big enough if you have hot water priority but you need a bigger cylinder.

 

[boilergp]

owners use the heating and water on different times but the boiler is not even heating all the radiators. it has an external pump and pump has been installed on the flow pipe, throwing the water away from the boiler.
could that be a problem?

 

[picasso]

What size pump and what speed have you got it on.

 

[boilergp]

I dont know the Pump size , its the red pump which u normally get in the combi boilers, and its set on max speed.

 

[boilergp]

I dont know the Pump size , its the red pump which u normally get in the combi boilers, and its set on max speed.

 

[mickyg]

The readings must have a difference of more than 25 degrees, otherwise the boiler will hold on low gas. The S code S.53 will be shown.

think you mean "less than"

 

[Beerlover]

Your'e right mickyg, Loving the beer again tonight

 

[mickyg]

Your'e right mickyg, Loving the beer again tonight

excuse accepted and respected