gravity system, loud noises

[Ted808]

Old boiler was replaced with Valiant 425. The customer is complaining- rightfully so, sometimes when the heating is on there is very loud noises from the radiator/pipes - that wasn't there before. I've been back and rebalanced the system, a few times - as it seems to keep loosing the equilibrium. I have no idea why....
- gravity system + old Y plan +new boiler with bypass +new pump set at 1. The noise sounds like horses galloping.
SO ...could it be the 3 port valve getting stuck? Is the pump too strong and over pumping, or is there a blockage? How do I check these things?
Or is it something completely different. The noise wasn't so bad when I went there but of course, a day or so later she called again and I could hear the noise in the background. I'm not sure how to test for the possible faults so I am turning to the panel of wise men on this forum who have more experience than me, please help. I have a few c*p photo's but maybe they'll help.
Cheers in advance

 

[Vee]

Is there possibly an old anti gravity valve still in the old heating return to stop back circulation? It may have broken up and/or the circulation is now reversed.

 

[Rightjob1]

Did you keep the same flow and returns of new and old?

 

[Ted808]

Did you keep the same flow and returns of new and old?

Yes! It sounds more like the 3port valve as now she's saying she didn't have hot water last night!

 

[jtsplumbing]

Also left in the old cylinder not always suitable for fully pump' systems should have got rid of the old gate valves as well wile system was empty, these old systems can be a pain sometimes , work fine for years as soon as you try to upgrade part of system it will start to play up.

 

[Ted808]

Well I went back, took out the tree port and checked function- it's working, put it back. Then read in one of my books that it maybe because all rads have trv's, advice was to change one to lock shields, to take up the pressure difference, when all the trv's shut/ open. Haven't heard back for nearly a week.....

 

[Rightjob1]

This worked even with your automatic by pass in already?

 

[sammathias]

Is your bypass fitted more than 1.5m from boiler? And flow and returns defo are piped up thw right way?

 

[jtsplumbing]

I know this may be a silly question and don't want to insult you But is the 3 port valve fitted the right way (B to hot water A to Heating)

 

[Ted808]

Well, I still haven't heard- but I'm going to ring customer to find out. Just by chance I was on another job- following the other guy who was kicked off the job, and the f+r were plumbed in the wrong way around! I figured it out after quite some head scratching. Anyway the thing is that it is a Y plan system and even tho it was plumbed wrong they still had dhw. So it lead me to think that maybe at the other place, the one with the he noise the f+r maybe wrong after all!! I didn't make those connections so can't be 110% sure. So I'll be checking that on my next visit. See the clue was that the 3 port is open to hw so that would work, but the heating.....? Maybe it works cuz new pump forcing enough water thru, but it's more very noisy. At this point I'm not sure if it's my active imagination or what.

This worked even with your automatic by pass in already?

YES?!

Is your bypass fitted more than 1.5m from boiler? And flow and returns defo are piped up thw right way?

. Nope, within 1.5 and as for the f+r ......... Almost 100% sure.

I know this may be a silly question and don't want to insult you But is the 3 port valve fitted the right way (B to hot water A to Heating)

Definitely

 

[sammathias]

. Nope, within 1.5 and as for the f+r . Almost 100% sure

Should be more than 1.5m away from boiler. read m.i

 

[Ted808]

Should be more than 1.5m away from boiler. read m.i

Really ? ok I'll go back and check, I'm sure I did it according to MI at the time...