Vaillant Ecomax 835 Hot Water Piping hot then luke warm

[guitarbonz]

Thanks Bunnyman,

interesting, where is the problem normally, is it with the pump or the electronic control (the dreaded pcb!).

I had the pump set to 100% until my GasSafe bloke came in last week, he reset it to Auto...

The pump does seem to be running ok....do you have any suggestions about how i could tell if it was stuck on low speed?

cheers

GuitarBonz

 

[Bunnyman]

Not usually the pcb they r sound on these. Even though u set it to max in the diagnostic the pump never reaches full output.. If u think about it when tested d40/41 it told u the temp diff was to great as the 831 bunny said.. As u have already changed the domestic ht exch an u have checked hoses etc for blockages an u have tested ntcs the only thing that can cause the poor circ is the pump.. As I said I have had a few doing this on the 835 an it is the only one with the variable speed pump.. It's hard to check the output but if mr an the 831 bunny had seen this thread earlier we would have told u to change the pump

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• Bunnyman
• 26 Mar 2010
• 499

 

[DANNIBOB]

CHANGED SEAL AND HOT / LUKE WARM STILL PERSISTS.
MY PROB IS THAT THE BOILER IS THE HIGHEST POINT ON THE SYSTEM AND PRONE TO AIRLOCKS. bUNGALOW WITH A DORMER AND BOILER IS IN THE DORMER...AH WELL GAS SAFE BLOKE IT IS...BUT THANKS AGAIN FOR REPLIES.

 

[guitarbonz]

Not usually the pcb they r sound on these. Even though u set it to max in the diagnostic the pump never reaches full output.. If u think about it when tested d40/41 it told u the temp diff was to great as the 831 bunny said.. As u have already changed the domestic ht exch an u have checked hoses etc for blockages an u have tested ntcs the only thing that can cause the poor circ is the pump.. As I said I have had a few doing this on the 835 an it is the only one with the variable speed pump.. It's hard to check the output but if mr an the 831 bunny had seen this thread earlier we would have told u to change the pump

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• Bunnyman
• 26 Mar 2010
• 499

I wish you had seen it earlier too! A pump doesn't cost as much as a heat exchanger

Vaillant technical were helpful but not particularly useful...i made a number of phone calls and sent emails.....the best one was the call i had advising me to change the plate heat exchanger....this was in relation to an email that i had sent telling them that i HAD changed the plate heat exchanger to no effect......

you live and learn......

many thanks for your help


Think i'll change the pump when i have a few quid to spare just to see what happens....there is obviously no "blockage" now.

 

[DANNIBOB]

ITS AN AUTO PUMP BUT YOU CAN SET IT TO MAX OUTPUT, USING AND GO TO D14, SET = TO 5 AND PUMP WILL RUN AT MAX CONSTANT...WORTH A TRY ?

 

[Agile]

If you press the i button during dhw and display shows S.53 or S.54 the temperature difference is too great and the boiler will enter 'get me home' mode for 10mins and just operate on low output to prevent any damage.

Bunny

Bunnyman, presumably thats what 831Bunny stated as quoted above, an excessive temp difference causing the boiler to stick in a low power mode.

The much earlier posts have demonstrated the usual DIY misunderstanding of just what X800 does not do.

To dissolve dirt in an HE, an acid is needed. This can be citric or HCl but as always acids need special care and experience of handling and use.

Tony

 

[guitarbonz]

[The much earlier posts have demonstrated the usual DIY misunderstanding of just what X800 does not do.

To dissolve dirt in an HE, an acid is needed. This can be citric or HCl but as always acids need special care and experience of handling and use.

Tony[/quote]

If you want to cast aspersions on DIYer's why do you bother with this web site? Your helpful contributions are brilliant but why must you spoil it by having a dig at folk whenever you get the opportunity?

I don't think that i had any "misunderstanding of what X800 does not do"....i read various other threads before i decided to at least give the whole system a thorough clean after incompetent original installation by a so called professional....i even read the instructions on the label and surprisingly for a DIYer was able to follow them.

Regarding cleaning the Plate Heat exchanger.....given that swapping the H/ex had no effect initially, that would indicate a blockage elsewhere, which gradually cleared over a few days of X800 and Fernox TF1 filtering. Combine a blockage with a slow running pump and you might have the ideal conditions for simulating H/ex failure. If i had the time and the inclination i could refit the old H/ex just to find out whether it was or was not knackered, but i can't be bothered anymore.

Incidentally my old man is a retired Rolls Royce Chemist and Metallurgist and like others posting on this site he is not impressed with using HCL to clean stainless steel; HCL and stainless steel do not mix, never mind the welds! HCL will attack stainless leaving microscopic pitting in the surface, ideal for trapping passing gunk...i believe he mentioned that phosphoric acid might be ok....but probably not worth the risk of handling it.

 

[Bunnyman]

Were not all bad mate most try an help

 

[Agile]

The point I was trying to make, not for you but for all those who read these forums, is that to dissolve dirt in boiler parts an acid is neeeded.

X800 is merely a chellating agent and does not dissolve anything.

Which acid depends on what type of dirt is causing the problem. Sometimes two different acids need to be used.

I was in no way suggesting that a DIYer should casually use citric or HCl as if they had the same effect regardless of the composition of the dirt.

To be effective with cleaning boiler parts the composition of the dirt needs to be assertained and then the best choice of acid made which takes into account the material of the boiler part, the concentration and the temperature of the acid.

Because of the dangers of handling acids I dont recommend any DIY use of acid although citric is the least hazard. But it has little effect on calcium products.

I hope your father has seen the TV program on making R-R aero engines with particular focus on the material and machining of the turbine blades.

Tony

 

[guitarbonz]

Point taken Tony.....i won't be doing anything with acids, even though they used to let us play with Conc. Nitric, HCL, Sulphuric and all the nasty caustic stuff in the school labs many years ago. Acid burns in the lab coat were almost a badge of honour.

As for whether Dad has seen the TV program, he has been retired 18 years, but in his day it was part of his job to sort out why turbine blades had failed or engines had caught fire....despite this he still hops on planes occasionally.

p.s. it is true they do fire supermarket chickens at the turbines to test the effects of bird strikes. Not sure your average vaillant boiler fan would cope

Signing off this thread forever now....

 

[Agile]

Turbine blades have come on a long way since then.

The latest ones are grown from a single crystal of the metal and operate above the melting point of the alloy but are internally cooled so that it does not melt.

They are machined to an acuracy of about the thickness of a human hair.

The outer cowl of the large fan impeller at the front has to contain any broken blades and starts as a 300 kg casting and is machined to about 54 kg which takes a couple of days. ( All figures approximate due to possible memory corruption ).

Tony

 

[DIY_James]

plumbase has some nice diagrams of this boiler, see

• http://www.plumbase.co.uk/vaillant-ecomax-835e-10000892-3549917/explodedviews?diagram=5