Vaillant "D" Settings help

[ScottishGasMan]

It's impossible to say exactly why its kettling. The likely hood may be that some sludge is in the hex, or the cleanser has slowly started pitting the heat exchanger pipes which leads to noise.

The noise can also be generated by generally poor flow, ie pump weakened or system blockage. But at the level in your video I reckon from an educated guess that a new hex will be required.

Unfortunetly they are well within their right to refuse this as clearly the system has not been flushed in accordance with insructions (I dont mean your work, I mean the installer leaving cleanser in)

The pump. Is it set for a constant flow or is it self modulating? these boilers should have a constant flow rate where possible so any smart pump should be set to a fixed speed (higher normaly on this type of heat exchanger)
Im sure most would agree smart pumps so far seem to be of questionable quality, compared to their older counterparts, WILO have an even more questionable reputation for the quality of their pumps so it cant be rulled out even if it was fitted at the same time as the boiler.

To add, Ive changed many pumps over the years as excess cleanser left in the system has damaged the bearings or caused the impellor seals to swell. Had one today, New boiler and full new system in march this year, water was like yours but darker, pump impelor was seized solid and covered in a dark coating along with the rest of the parts.


Firstly I'd advise speaking to the installer to see what help they could offer. Unlikely they will run out to buy you a new hex, but if they have a good relationship with the area Rep they may be able to swing a repair subject to them correctly flushing out first and possibly replacing pump. But thats very dependant on the installer. Also you would be best trying to contact vaillant to see where you stand now on future warranty issues and if/how you can resolve this (have they actually visited and seen it yet?)

As far as claims go, I can not advise you on legal matters. But I expect given the number of vairiables such as time since install, potential for 3rd party interference, agreement and proof of work done at install, that you would be looking at a minefield that would cause a lot more grief and money than just paying for a repair.

 

[ScottishGasMan]

Also out of curiosity, when its making the big noise, what are your D40/D41 readings now?

 

[pd1971]

After just firing

D40 shot straight up very quickly was at 49 after a few seconds it was at 63
D41 was at 49

As far as I'm aware the pump doesn't have an option to change the pump self modulating or constant flow ??

I do hear the pump sometimes slow & speed up, even though set to three
so as a guess it is self modulating

Just done a video of the pump, sometimes makes a noise like there is air or something rattling in the pump then it stops after a while

http://youtu.be/hQwLH6DcpNU

Is there a way to check flow rate in the d values?

Thanks again for you advise

 

[ScottishGasMan]

The flow rate can be estimated with enough info yes.

1. We need to know D.0 - Probably still 8kw but check and confirm.

2. You need to run the boiler constant at 8kw without it modulating, turn CH on, make sure all radiators are on and up full at TRVs. Press lower two buttons on facia to activate chimney sweep mode (will lock boiler to run at whatever D.0 is set to)

3. while this is happening keep it locked, and go to D.Codes, find D40/D41 and post back what it is with the boiler running as above.

Knowing the Termperature entering the HEX, and whats Leaving it, a best estimate can be made on what flow is going through it based on it giving this temp rise using approx 8kw.

 

[ScottishGasMan]

For Example, The D Values above

63/49
at 8Kw

Would mean approx 490 Litres an hour passing through the Hex, quite a bit short of the 773l/hour reqd for a 418 Thus the noise would be attribitued to low water movement rather than a hex fault (although the restriction its self could be in the hex, it would not be a case of the hex making noise for no reason in the case of it being that noisey with the correct flow rate, it could be said that the hex its self has developed a fault)

 

[pd1971]

OK hope this helps, did as stated in chimney sweep mode all rads on with TRVs open

D0 is at 7KW turned it down on advise from engineer due to the kettling

Values D40/D41

starts @ 28/18
1 min 27/17
2 mins 30/20
3 mins 33/23
4 mins 35/25
5 mins 37/27
6 mins 39/29
7 mins 41/32
8 mins 43/34
9 mins 45/35
10 mins 46/37
11 mins 48/39
12 mins 49/40

 

[ScottishGasMan]

Thats approx 600 litres an hour, say we take the average differecne between D40/41 to be 10 degrees.

It is still under the expected flow rate by over a hundred litres an hour.

But I reemphisise that only confirms that there is less than the correct water flow, this could still be a bad pump, restriction in your pipework or in the hex.

 

[pd1971]

Many Thanks, what would you suggest I tried 1st change the pump? If so can you advise which Grundfos pump to buy?

 

[ScottishGasMan]

Personally I always go for a grundfos 15-60, that way it has a decent bit of push and can be turned down if you need to.

Personally, id flush the system with fresh cleanser for a few days, then empty the lot out/refill circulate and repeat untill the water draining from the system is clear and colourless. then on last fill when you know system is good, then fit the new pump.

If theres still noise contact vaillant under a warranty call and at leas the engineer can see that the waters clean and you have a decent new pump

 

[gazdaz36]

You simply cannot install these boilers on anything other than a clean system. The level of cleansing required on an old system is, in my opinion unachievable for the level cleanliness required.

Unless of course you're lucky enough to have little or no debris in it to start with.

Funny that I put my 418 in 3 years ago on a 30 year old system and surprise surprise no noise. System wasn't power flushed it just had fernox cleaner run through it after installation.

Biggest problem with noise on this boiler is installers putting it on the wall, filling it up, giving it a half hearted basic flush and leaving it at that. Oh yes and filling in the benchmark with a load of bull manure.
Firstly these boiler have a habit of being over rated if people bother to do a gas rate. Secondly D0 is usually left at 18kw when it isn't needed and finally the auto bypass is never set to give the correct temperature differential of a maximum of 20 degrees. All this helps to bake any dirt on the inside of coils of the heat exchanger, which then flake off block the heat exchanger and also the pump impeller causing poor circulation

 

[pd1971]

Personally I always go for a grundfos 15-60, that way it has a decent bit of push and can be turned down if you need to.

Personally, id flush the system with fresh cleanser for a few days, then empty the lot out/refill circulate and repeat untill the water draining from the system is clear and colourless. then on last fill when you know system is good, then fit the new pump.

If theres still noise contact vaillant under a warranty call and at leas the engineer can see that the waters clean and you have a decent new pump

Cheers, what cleaner would you recommend X300 x400 or x800 or just drain & flush with clean water?

Would a Grundfos UPS2 15-50/60 130 or the Grundfos Alpha 2L 15-60 be the one to go for?

Many thanks again for your advise

 

[scoobydo123]

seems strange how it heats up so quickly in the first 15 or so seconds in the video and then seems to stabilise, almost like the boiler is not seeing the whole system during the initial fire algorithim where it is firing at 85% of max rating. You sure you MV (motorized valve is not lazy). Are you s plan or y plan.

 

[ScottishGasMan]

Both those pumps are 6m heads so doesnt really make any difference, think the ups will be cheaper so go for that as your not going to use the extra features, just set it to fixed speed

X800 has got the best chance of breaking up a restriction, but it's leathal to pumps which luckily your replacing after so just be sure to fully drain and fill enough times till water circulating is crystal clear and completely colourless.

 

[pd1971]

seems strange how it heats up so quickly in the first 15 or so seconds in the video and then seems to stabilise, almost like the boiler is not seeing the whole system during the initial fire algorithim where it is firing at 85% of max rating. You sure you MV (motorized valve is not lazy). Are you s plan or y plan.

Hi Scoobydo

Many thanks for your reply

It's the only thing that hasn't been replaced as yet from the old system, so would that be the reason why the temps go up so quickly

Is there a way to test the MV being slow?

I've not sure which plan I'm on, just had a look on Wiki & I think its a Y plan

I'll upload a video of the 3 way value shortly

Have ordered a Grundfos UPS2 15-50/60 pump

Going to clean out with x800 for a few days then, flush & then refill with x200 & x100 & install a new pump

 

[ScottishGasMan]

Wouldnt make any difference if the motorised valve was slow as on a Y plan is never "shut" completely. Only closed over one path but theres always a route through the valve.