Vaillant ecotec pro 24 - Hot water not hot enough

Joined
6 Mar 2009
Messages
3
Reaction score
0
Location
London
Country
United Kingdom
Hi I have a vaillant ecotec pro 24 combi boiler and the hot water temp is only 40 degrees coming from the hot tap which is next to the boiler.

I have replaced the NTC sensor which clips onto the DHW heat exchanger
but this has made no difference. The boiler is just over 2 years old (outside warranty) the central heating is fine and the radiators get hot.

Any thoughts would be much appreciated.
 
Sponsored Links
Joined
24 Jul 2003
Messages
24,294
Reaction score
1,417
Location
London
Country
United Kingdom
Gas valve needs adjusting, supply gas pipe undersized/blocked or more likely, the secondary heat exchanger is blocked on the boiler water side.
 
Joined
18 Oct 2007
Messages
10,587
Reaction score
1,353
Location
Kent
Country
United Kingdom
Hi I have a vaillant ecotec pro 24 combi boiler and the hot water temp is only 40 degrees coming from the hot tap which is next to the boiler.
What is your flow rate in ltres per minute?

The Ecotec Pro 24 will raise the water temperature by 35°C at a flow rate of 9.4 litres per minute. If the flow rate is faster, the temperature rise will decrease proprtionately. But if the flow rate is slower, the temperature rise is controlled to 35°C for safety reasons.
 
D

Deleted member 105431

But if the flow rate is slower, the temperature rise is controlled to 35°C for safety reasons.
nonsense. if the flow rate decreases the delta T increases at a directly proportial rate upto a maximum of 65 deg dependunt on the dhw potentiometer/knob.
 
Sponsored Links
Joined
18 Mar 2008
Messages
1,467
Reaction score
994
Country
United Kingdom
Turn the hot water knob up & and down, does the selected temperature in the display move up or down corresponding to you moving the knob? If not the spindle of the knob has snapped and the temperature is set low. Good starting point for poor dhw on this model.

Knob will require replacing if thats the case

Bunny
 
D

Deleted member 105431

Turn the hot water knob up & and down, does the selected temperature in the display move up or down corresponding to you moving the knob? If not the spindle of the knob has snapped and the temperature is set low. Good starting point for poor dhw on this model.

Knob will require replacing if thats the case

Bunny

as the bunny says; a temp fix would be to swap with the ch knob.
 
Joined
18 Oct 2007
Messages
10,587
Reaction score
1,353
Location
Kent
Country
United Kingdom
But if the flow rate is slower, the temperature rise is controlled to 35°C for safety reasons.
nonsense. if the flow rate decreases the delta T increases at a directly proportial rate upto a maximum of 65 deg dependunt on the dhw potentiometer/knob.
Accepted. But why would anyone want to have the water temperature at 65°C?

It's different if the hot water is stored, as then a temperature of 60°C is used because it it high enough to reduce the possibility of Legionella and not so high as to encourage limescale deposits from hard water. The disadvantage is that you then have to mix the hot with cold to bring the water temperature down to a safe level for baths etc - somewhere between 35°C and 40°C.

Assuming the user is sensible and keeps the temperature control at between 35°C and 40°C, the water temperature will not exceed the set level, irrespective of the flow rate. In any case, most people want to fill their bath quickly, which means a high flow rate and consequently a low delta T.
 
D

Deleted member 105431

But if the flow rate is slower, the temperature rise is controlled to 35°C for safety reasons.
nonsense. if the flow rate decreases the delta T increases at a directly proportial rate upto a maximum of 65 deg dependunt on the dhw potentiometer/knob.
Accepted. But why would anyone want to have the water temperature at 65°C?

It's different if the hot water is stored, as then a temperature of 60°C is used because it it high enough to reduce the possibility of Legionella and not so high as to encourage limescale deposits from hard water. The disadvantage is that you then have to mix the hot with cold to bring the water temperature down to a safe level for baths etc - somewhere between 35°C and 40°C.

Assuming the user is sensible and keeps the temperature control at between 35°C and 40°C, the water temperature will not exceed the set level, irrespective of the flow rate. In any case, most people want to fill their bath quickly, which means a high flow rate and consequently a low delta T.

I see your point but thermostatic showers give better flow rates when the hw is around 50/55 deg c and very few customers have the hw set at 40 in my experience. In holland where different regs apply 40 deg c is the max a boiler can be set to for dhw.
 
M

marsaday

hello, i have the same problem and wondered if the gas flow was to blame.

The water comes on hot and then goes luke warm.

should i start a new thread or use this one though? i will post my details.

my boiler is 16 months old and so out of warranty. the engineer just uprated the gas flow as the piping didn't allow enough gas to get through. He said he should go upto 28mm for a 3-4m run, but the plants were in the way (gas pipe going up side of house) and so we both agreed on uprating the gas flow from the mains.

everything has been fine until this weekend. Is it likley to be this gas problem or the diverter valve.

our boiler is the ecotec plus 837

ps. the heat exchanger was changed in march under warranty. the system was crystal clear and so must have got a bit of crude in when fitted. a magna clean was fitted and the system was power washed at install.
 
D

Deleted member 105431

hello, i have the same problem and wondered if the gas flow was to blame.

The water comes on hot and then goes luke warm.

should i start a new thread or use this one though? i will post my details.

my boiler is 16 months old and so out of warranty. the engineer just uprated the gas flow as the piping didn't allow enough gas to get through. He said he should go upto 28mm for a 3-4m run, but the plants were in the way (gas pipe going up side of house) and so we both agreed on uprating the gas flow from the mains.

everything has been fine until this weekend. Is it likley to be this gas problem or the diverter valve.

our boiler is the ecotec plus 837

ps. the heat exchanger was changed in march under warranty. the system was crystal clear and so must have got a bit of crude in when fitted. a magna clean was fitted and the system was power washed at install.

837's have a 2 year warranty; call vaillant direct for a free callout.
 
M

marsaday

thanks. but what if it is the fault of the lack of gas. this will not be covered i assume.


Called them and it does have a 2 yr W, so thanks for that.

i hope it is a problem with the boiler now and not a gas supply issue :)
 
D

Deleted member 105431

thanks. but what if it is the fault of the lack of gas. this will not be covered i assume.


Called them and it does have a 2 yr W, so thanks for that.

i hope it is a problem with the boiler now and not a gas supply issue :)

if the gas supply is undersized it would never have worked properly so wait and see what the vaillant man says would be my advice. ;)
 
Joined
10 Jun 2009
Messages
5,225
Reaction score
1,015
Location
Suffolk
Country
United Kingdom
My advice is to check the flow rate from the hot tap, your 24Kw combi is going to struggle if flow ratew much more than 10-5 ltr/min

A 28 Model would be the Minimum size I would recommend
 
Joined
26 Jun 2004
Messages
64,319
Reaction score
4,690
Location
London
Country
United Kingdom
I expect he has just gone to bed early.

This is a typical case of people making lots of possible causes when the most basic of information at the outset would have elimated most.

Just knowing the temperature and flow rate would have cut down the likely causes to about two!

Tony
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top