Trickling noise when pump comes on

[Wildbeard]

Hi can anyone help on the following.

The company I work for have installed. A Baxi megaflo 24kw system boiler with a premiere plus 300 litre unvented cylinder. All pipe work is new and pipe sizes have been followed to the Baxi heating drawing, the property is on a new build development. The customer first complained of a noise within the pump, heat team were called and replaced the pump, problem still persisted, heat team called back out stripped boiler down and found the automatic bypass on the boiler was constantly open replaced auto by pass problem solved. Customer still complained that boiler was noisy, heat team came back out replaced boiler. A few months later the customer complained boiler was noisey, I attended myself the only noise I could hear was when boiler first fired was a water movement noise like a trickling for the first ten seconds , in my opinion this is normal as the pump is working hard to get the system circulating ( 19 rads on system ) Sytem also has a Honeywell bypass in airing cupboard drained down checked operation of bypass all ok. The builder then called a independent engineer who asked us to alter auto air vent in cupboard which we did, customer still complaining of water trickling when pump kicks in. I have been a qualified engineer for over 20 years, customer is now going to get his own engineer in which he is welcome to do, am I missing something ?

 

[king of pipes]

Sounds like it's a bit small to me bud maybe struggling to achieve a satisfactory tempreture so wont modulate down 19 rads x2kw apiece on average plus the coil in the cylinder is to small do a gas rate and check flow and return tempretures across the boiler be interested to know what return tempreture you get when on full demand and you will need to add another expansion vessel . Hope this helps

 

[Wildbeard]

Hi sound only happens when system cold, checked expansion vessel when hot and cold, pressure hardly raises a quarter of a bar when system upto full temperature.

 

[Wildbeard]

Sorry ment to add primary pipework 28mm both heating circuits doing nine to ten rads respectively, house is a new build so most rads aren't that big.

 

[king of pipes]

Thats the trouble with system boilers the pump being inside the casing your stuck with what you have got , do the calculations on the system the kw needed at full rate you can work out expansion vessel size from there . Can't see there's much you can do without adding costs, don't get caught out have the information ready because if the independent engineer starts finding faults you need to have answers to satisfy your customer. All the best bud .

 

[Last Plumber]

You need to calculate the index circuit.
Start with that.
It may be better to put LLH or PHE in and external pump.
If the boilers pump is struggling to get things moving you will hear it until the flow increases.

 

[ShaunCorbs]

19 rads on a stnd 15-60 will never work

 

[Wildbeard]

Hi, that's why I hate system boilers never saw the point of them, when everything could of been done in the airing cupboard. At the end of the day it's on a new build we have only worked to heating drawing supplied by manufacturer and developer, have spoken to their design department who ensure me that the pump expansion vessel is more than adequate for volume of water in system, They have also confirmed that in a email. Going to let customer get independent engineer and go from there. Cheers

 

[king of pipes]

Cant help you anymore than we have bud if you have coverd yourself then best of luck .