I have Vaillant TURBOmax Plus 828 E combi boiler. I had a problem with a shortage of hot water, but have resolved this by flushing out the DHW heat exchanger with strong limescale remover I read about on the net. My current problem is that the temperature of my hot water never gets really hot and goes up and down, I have watched the diverter valve,this did not seem to move, so I detached the connections and the same happened. I think that the valve has become stuck partially open which will be affecting the temperature. can anything be done other that replace the unit? regards Dave
Vaillient boiler TURBOMAXplus 828 E hot water temperature
- Thread starter davegreen76
- Start date
Thanks for the reply, I have just cleaned out the HE again and the flow was good from each side, I checked the condition of the DV and it seemed to move quite freely. once I re-connected the system I watched the DV working correctly in and out as I called for the hot water. I still have the problem of the water not getting hot enough and not staying at a constant temp. I will have to turn it up fully, which will cause the HE to block up really quickly. I have been running the heating system and the rads seem ok but not as hot as they used to be. Do you think it is a gas issue cutting in and out?
Not been serviced since I bought the house, 1.5 years ago.
Not found any info on temp sensors anyone help?
Cheers
Not found any info on temp sensors anyone help?
Cheers
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Hi
with a hot tap on full, and the hot water temperature dial on max, what temperature is displayed on the boiler LCD? Wait about a minute and it stabilises. On an 828 it should be around 70C - 76C.
Bunny
with a hot tap on full, and the hot water temperature dial on max, what temperature is displayed on the boiler LCD? Wait about a minute and it stabilises. On an 828 it should be around 70C - 76C.
Bunny
thanks,
Have just run as advised, LCD reading 81c constant.
Actual water temp is a slightly warm constant 37c.
Was Fluctuating this morning but is now a constant temp.
Have just run as advised, LCD reading 81c constant.
Actual water temp is a slightly warm constant 37c.
Was Fluctuating this morning but is now a constant temp.
Its not often I would disagree with anything Bunny says but that figure is not very helpful ( and I think its higher than most would find ).
Whats more relevant is the DIFFERENCE between the hot water temperature and that reading which is just the primary input temperature.
The diference should not be much more than 15-20°C if the plate is clean.
A good idea of the condition of the plate can be obtained from the boilers measurement of the flow and return temperature. They should be about 10-15° difference. If its a lot higher then the plate may be blocked or the pump blocked or failing.
Tony
thanks,
how or where can I measure the flow and return temps?
how or where can I measure the flow and return temps?
have measured the temps on the pipework after it has been running for a while, the heating side is about 10c different from in to out.
I then ran the hot water and the outgoing pipe only ever reached 34c.
Any one know the best place to get a new DHW heat exchanger for this model?
I live in a really hard water area, what is the best cost effective way of reducing the limescale into my system?
I then ran the hot water and the outgoing pipe only ever reached 34c.
Any one know the best place to get a new DHW heat exchanger for this model?
I live in a really hard water area, what is the best cost effective way of reducing the limescale into my system?
I dont think of Norfolk as a very hard water area.
You did not say what the primary temperatures actually were. However a differential of just 10% indicates there is no blockage on that side.
The apparently much lower DHW temperatures indicates a lime ( calcium carbonate ) deposit on the secondary ( hot water ) side.
That often results from a leaking hot tap !
Thats very easy to clean with hydrochloric acid. Its readily available as Spirits of salt in many hardware stores at about £2.50 for 500ml at a strength of 32%.
Dilute the acid in two times its volume of water, pour acid into the water, and use cold by pouring into the secondary side of the HE and agitating. Be aware it could buble.
You need to wear eye protection and rubber gloves etc.
Tony
You did not say what the primary temperatures actually were. However a differential of just 10% indicates there is no blockage on that side.
The apparently much lower DHW temperatures indicates a lime ( calcium carbonate ) deposit on the secondary ( hot water ) side.
That often results from a leaking hot tap !
Thats very easy to clean with hydrochloric acid. Its readily available as Spirits of salt in many hardware stores at about £2.50 for 500ml at a strength of 32%.
Dilute the acid in two times its volume of water, pour acid into the water, and use cold by pouring into the secondary side of the HE and agitating. Be aware it could buble.
You need to wear eye protection and rubber gloves etc.
Tony
I have cleaned out my DHW about six times since I moved in and have made sure that when I flush it out I get a good flow out of each side.
I'm presently getting a good flow on the hot water side but its only coming out at 34c. This is just about bearable in the shower but seems to be getting slowly worse.
Have been looking around the net and found a price of £85 for a new DHW, hope this will solve my problem.
I'm presently getting a good flow on the hot water side but its only coming out at 34c. This is just about bearable in the shower but seems to be getting slowly worse.
Have been looking around the net and found a price of £85 for a new DHW, hope this will solve my problem.
I'm afraid it won't.
If you've cleaned it, you shouldn't see ANY black stuff inside. A good flow means nothing, really. Use citric acid or phosphoric acid descaler, or hydrochloric as advised.
Even if it isn't spotlless, you should get much more than 34º AS LONG AS you aren't taking the water too fast. MEASURE IT and take it at about 10 litres per minute. At this time of year the incoming water is cool, so you can't heat as much to bath temperature, which is about 45º.
Then you MUST look at this,, as advised:
Thanks
To clean out my DHW I have been using ferox limescale remover which I was advised was the correct stuff for the job
At 34c (full flow) i'm getting about 9 litres a min
At 42c (quarter flow) i'm getting about 2.5 litres a min
The flow pipe doesn't seem to change in temp when you run the hot tap.
To clean out my DHW I have been using ferox limescale remover which I was advised was the correct stuff for the job
At 34c (full flow) i'm getting about 9 litres a min
At 42c (quarter flow) i'm getting about 2.5 litres a min
The flow pipe doesn't seem to change in temp when you run the hot tap.
We cannot assess the situation with only two measurements.
We need FOUR!
Flow and return on heating side.
Inlet and outlet on DHW side with the flow rate of about 9 li/min which is what the boiler can heat at this time of year to about 42°C.stated.
In ADDITION we need the gas rate. You measure this at the meter. See FAQ for instructions on how to do that.
You do not assess a plate HE by looking at the water flow through it. Its the actual heat transfer which is relevant.
If you think you have properly cleaned it then why do you think a new one will be any better?
They are totally cleanable using the right techniques.
Tony
We need FOUR!
Flow and return on heating side.
Inlet and outlet on DHW side with the flow rate of about 9 li/min which is what the boiler can heat at this time of year to about 42°C.stated.
In ADDITION we need the gas rate. You measure this at the meter. See FAQ for instructions on how to do that.
You do not assess a plate HE by looking at the water flow through it. Its the actual heat transfer which is relevant.
If you think you have properly cleaned it then why do you think a new one will be any better?
They are totally cleanable using the right techniques.
Tony
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