K3 1600x600

[johnwa]

Hi all I have fitted the radiator the back and center panel are even heat but the front one is cooler at the bottom, I was told it was a flow problem but it is the only live radiator on my system the rest have been turned off, the boiler is a new Valliant 24 KW and the system had a power flush
I have changed the radiator but the problem is the same.
Any ideas guys?

 

[gas112]

what size pipework is supplying it , both valves fully open

 

[johnwa]

Hi thanks for replying 15mm pipework I have run with the valves open and various turns on the lock shield, the straight run to the rad from the boiler is app 10m, I had a K2 installed before with no problem I just needed a bit more heat, is a booster pump the answer if I ned more flow?

 

[Johntheo5]

This "cold" panel seems to be a feature of the K3, someone on one of these sites increased the pump head to give a constant 6M on a heat only boiler which largely solved the problem but it seems a shame to have to run with this head as most systems do fine at a pump head of 3 to 3.5M, also your Vaillant can only run at a maximum head of 4.0M (400 mbar), the default setting might be as low as 2.0M so check the following D parameters, D.170, D.171, D.172, D.173, D.174 & D.175.

 

[johnwa]

Hi John thanks I have checked and it is on 400mbar also there is a motor speed adjustment for when you need a bit more flow, I have screwed it as per installation manual and I have a more uniform heat on the outside panel. So I may fit an external pump to save the internal pump working harder.

 

[Johntheo5]

What do/did the flow/return temps D.40&D.41 read with the K3 on its own?
Have you any particular pump in mind for boosting and how do you propose to stop/start it?

 

[johnwa]

Hi John no I didn't measure with just the K3 in circuit.
I am looking at the Trident https://www.tridentpumps.co.uk/product/automatic-boosting-pump-with-integrated-flow-switch/ , fitting it after the 2 port on the heating side only (S Plan) operating it from the 240v supply that opens the 2 port. I do not see any point in fitting the pump on the whole system what do you think?

 

[Johntheo5]

Are you thinking of using it to feed all the rads on the heating side?, if so, how many rads, including the K3, if you are then you can just use the 2 port valve end contacts to start/stop the exra pump. I can't find any info on that Trident but IMO you might be (far) better off spending a bit extra on a pump like mine, a 6M Wilo Yonos Pico where you can set the pump to CP (constant pressure) control incrementally, in 0.1M steps between 0.5M and 5.5M, which will give you very good control of head pressures etc, you could, if you prefer just go for a simple 3 speed pump settings of say 2M, 4M and 6M, the Wilo also gives this option.

The K3 rad has a rated output of 3.82kw (13.042BTU), to get its full rated output would require flow/return temps of 75C/65C and a flow rate of 5.48LPM but if you are happy enough using flow/return temps of 65C/50C (more efficient running) its output will then be 2.63kw at a 2.51LPM flowrate.

What pump is currently installed and what setting is it on?. what is the boiler flow temperature?. what is the make/model of your boiler.

 

[johnwa]

Hi John on the microbore upstairs fed by 2 x 22mm Manifolds 4 rads 2 towel rails, downstairs is 15mm 6 rads inc K3 and a towel rail.
The Boiler is LPG Vaillant Ecotec Pro 625 installed by a gas-safe engineer 5 weeks ago, I installed the system when I built the house 1985-1988 the K3 is for an extension where a K2 was insufficient. I have the flow set at 70 but can increase/adjust when it all runs okay.
I will have a look at the 6M Wilo Yonos Pico. The pump is the one in the Vaillant no other external one yet!
Thanks for all the input John .

 

[Johntheo5]

Have you 2 x 2 port valves on the CH, one for upstairs, the other for downstairs?, if so, do you intend to install the booster pump on the downstairs circuit only?

Edit: can you post a link to the actual boiler model.

 

[johnwa]

https://professional.vaillant.co.uk...otec-plus-610-615-620-625-630-635-154880.html mine is the 625.

I have a Hive system, there is one valve for HW the other CH up and down, I can't separate John.
The original Valliant fitted 10 years ago was done by a Gas Safe engineer I think his name was Stevie Wonder its terrible solder everywhere so when I fit the pump you recommended I will tidy it up. The new boiler was plug and play like for like.

 

[Johntheo5]

You said you had a ecotec pro but the attachment is for the ecotec plus, a lot of the d parameters will probably be the same anyway, so you might fire up the boiler in CH mode ( a few minutes should be enough) and check the actual pump speed d.015 (%), check hydraulic operating mode d.170, pump status d.018, permanent or eco (or if it shows 1 then fine) and any d parameter that you think is relevant to the pump.

 

[johnwa]

Sorry John it is a plus " a grey moment" I will do the checks TU

 

[Johntheo5]

Is the 10M run of 15mm piping from the boiler to the K3 dedicated to it or is it feeding (other) rads as well?
It might be worth just running the K3 only for awhile and check d.040&d.041 as well as the pump speed d.015 again, also just feel the return at the rad as the boiler return temp d.041 will more than likely read much higher than the actual return due to the internal by pass but at least you will get some idea of whats happening even though a bit of a pain shutting off a lockshield valve on each rad.

 

[johnwa]

The K3 is on a run with 2 small rads and a towel rail John they are all under an insulated floor, I will give it a go thanks again