Vaillant EcoMax 828 DHW flow rate

[vloft]

Hi, I am newbee to this site, but before I call the plumber I thought I would try you guys. Moved into a flat with this combi boiler, which is less than 12 months old. Every thing seems to work ok, except the presure at the hotwater tap is not very high, bit of a pain with the shower. I thought with it all being on mains pressure it would be the same as the cold water pressure, which is very good. When you open the hot tap, there is an initial high flow and then it's a steady flow at lower pressure. Is this just a charecteristic of this type of combi boiler or do I have a problem. Any help/advise most appreciated.

 

[HarrogateGas]

Need more info, you will certainly get less flow out your hot taps than your cold, the boiler has a flow regualtor fitted. You need to measure the flow per minute and the temp rise, compare this with manufacturs specs to see if there is a fault or not.

 

[vloft]

Thanks for coming back. It makes more sense now you mentioned that these boilers have a flow regulator. I looked at the spec and it has two settings: DHW dt 35c with flowrate 11.5l/min & factory set dt 42c with flowrate 9.6l/min.

I suspect mine is set at the factory default of 9.6l/min. Is there a way of changing this to get the max output stated 0f 11.5/min. If so what do I need to do. I had a look at the cold water feed valve, behind the dropdown control panel, but not sure what needs to be adjusted any help on this would be fantastic.

 

[HarrogateGas]

Its not adjustable..its just telling you that at 11.5 literes a minute you will get a 35degree temp rise and at 9.5litres a minute you will get a 42 degrees temp rise.

thus if your mains into the house (what comes out the cold taps) is at 5 degrees and you hot tap is running at 11.5 litres a minute you will get hot water at 40 degrees. (5 degrees add the temp rise 35 degrees = 40 degrees)


i make it sound complicated........its not.


You have (in my opinion)!! the best Combi boiler on the market. It should be trouble free for years to come.

 

[vloft]

Ohh........that's not what I wanted to hear. I thought one of the advantages of a combi was that the DHW would be at mains pressure. Is there anything I can do to increase the flow rate or is that the best I am going to get

 

[HarrogateGas]

Pressure and flow are different.........it IS at mains pressure. But the flow is reduced in order it can be heated suficiently.

 

[ChrisR]

If I've got the right boiler (it's late!) you may have a faulty Diverter Valve. Part no 252457. (Seem to be 2 different Ecomax 828's??)
Start when the CH has been off a good while so all the pipes under the boiler are cool.

Turn the HW tap on full and grope the leftmost (fat) pipe. It shouldn't be getting hot. If it is, energy is going to the rads when it shouldn't and you probably need a new DV.

This part has been deplorably unreliable since it was introduced several (6?) years ago. Vaillant have had at least 5 different versions of it in their boilers and they're still giving problems. It's about time they stopped doing product development at their high-paying customers' expense.

Theirs are also about the only current combis of any supposed quality which do not fully modulate on HW. Bit of scale and you're hopping in and out of the shower.

I used to fit Vaillants for preference, but have got fed up with them ALL going wrong (90% DV's) inside a year or two. Stuff em.

Hope you have the Ecomax with the 014631 DV!

 

[HarrogateGas]

If it is less than a year old the Divertor Valve will be fine, this boiler is 100% sorted from about 2.5 years ago. If the divertor valve was gone (the ball inside used to swell) you would be complaining that your hot water is not hot enough or erratic, it would not effect flow in any way.

If its under 12 months old its still under warrenty, get them out.


The Ecomax range ARE fully modulating.

 

[ChrisR]

Thanks- did they change the model number? Vaillant seem to be less than crystal clear over their model designations!

Vaillant told me, a month ago, that they only modulate in response to altering flow - aquasensor department. If the heat can't get out of the boiler due to secondary heat exchanging problems, the burners just go hi-lo-hi-lo. I raised the question because I caught an Ecomax doing it. (Fixed by cleaning out the black from the dhwhe). I was asking about an Ecotec - they're the same apparently.

Vaillant's haughty reply was that their boilers are for clean water. Not for old systems then, says I. "Powerflush" says Vaillant. Fernox says you can get "up to 80%" of dirt out of a system - one would assume that means rather less, in a non-ideal situation.

The turbomaxes were certainly very fussy about any muck in the dhwhe. They are of course bigger on the later models which must help.

 

[HarrogateGas]

So they DO fully modulate on hot water......... Any new condensing boiler requires a clean system, this is normal practise in the trade. The Aqua sensor you refer to (the Halls sensor) is by far the most accurate way of maintaining constant hot water temp. The boiler not only knows how hot it is but also how much flow is going through it to give a precise modulation.

The Vaillaint is in my view the best due to a, Its parts (quality) and b, over a Bosch they go that extra bit and sound proof the case, simpler customer controls etc.



The Ecotec is a cheaper varient of the Ecomax. Cheaper in the sense it has plastic componants (pump manifold etc). Its much like a Glowworm CXi and proberly leaks just as much water!!!!

 

[ChrisR]

So they DO fully modulate on hot water

I have just explained how they don't, not in response to the temperature of the hot water output. That is what Vaillant say, and that is how they behave.

Glowworms DO, though!

Are you saying "no condenser" can be used on an old system? Are you claiming that dirty old systems can be cleaned better than the 80% Fernox claim?

A certain amount of dirt is reality in any old system. Turbomax Plus's (with Aquasensor) aren't coping with it. As I say, h/e's are bigger now which will help a bit.

-------

The Aqua sensor you refer to (the Halls sensor) is by far the most accurate way of maintaining constant hot water temp.

In a perfect world, it might be useful. The open-loop control system lets it down.

The Hall sensor is part of the fan assembly nothing to do with water temperature.

 

[HarrogateGas]

The Halls sensor is also part of the Aquasensor..........the turbine turns ,the halls sensor picks up how fast it is turning , and bingo the boiler knows how much water is passing thrugh it and thus how much gas to pull through. A fully modulating boiler if ever i saw one!


Vailliant part number 71-1933 Sensor-Hall VUW 356-C

Belive me its not an Aqua sensor.....its a Halls sensor

 

[ChrisR]

On further digging - necessary because Vaillant are as incompetent at doing proper documentation - yes there is a Hall (not halls) sensor as part of the Aqua Sensor. Aqua sensor (they also incompetently call it an Aqua-Sensor or Aquasensor depending where you look), is Vaillant's name not mine. The Hall sensor doesn't appear in all their literature - apart from the fan one.
It doesn't matter what it's called - the point is that the design it's in, doesn't work. If the water leaves the boiler too hot the flames don't fully modulate. That is what Vaillant say, whether you like it or not. The users will just continue to say "this is a cr*p boiler" and they have a point. Most if not all Vaillant's competitors wouldn't give that problem, they fixed it years ago.

You seem to be unaccountably loyal to one of the versions (which Vaillant are not competent to clearly name) of this boiler!

Vaillant have lost credibility by proving that they can't be bothered to use a reasonable DV to replace 252457 (some turbomax and some ecomax)after several years. Why they stick to Giannoni for that piece of junk is beyond everybody. They must think it's good for business. The only other part I can think of which was so bad for so long is the Suprima pcb - at least B-P have replaced that.

I expect Vaillant have built in some other guaranteed-to-fail garbage into their latest boilers - which will continue to fool some of the people some of the time.

Just off to a diverter - again - on an earlier Turbomax (011289). I think it'll be the boiler's fourth. There IS a pattern here.

Oh - and their customer service has gone through the floor. Apart from that they're great!

 

[HarrogateGas]

All a matter of opinion I suppose. i have been fittting Ecomax's for about 4 years now...Its the only boiler I know I can fit and forget. Maybe i do the job properly and flush the system out well before i install this boiler. Who knows?

 

[vloft]

The debate seems to have widened a bit!! But no matter lots of good info. The boiler I have was a replacement for an indirect system and not sure how well the system was cleaned, before the combi put in. Just in case I want to give it a thorough cleaning, what is the best product to use