A sorry tale? Worcester Bosch Greenstar 24i and hot water

Hi Everyone,

I'm looking for opinions please....

I've just had a worcester bosch greenstar 24i installed in two flats. My problem concerns winter hot water temperatures.

My installer fits these boilers as normal practice in flats of my size and maintains he gets the hot water coming out at 55C, except for my two flats where we are getting 45C.

Cold water temp is currently 7C, so we are seeing arise of 38C, which is above the 30C rise in the spec. The Worcester technical support line says they generally see a 40C rise that they see with these boilers. For reference (a) the flow rate was 9 litres per min, and (b) the specification says "domestic hot water specific rate for 30C rise 11.5 L/min."

My point (and I took this up with Worcester tech) is that every house, flat and hotel I have been in in the UK is that having a bath or shower the norm is that one has to dilute the hot with cold for a decent hot bath and shower. I think that at 45C is too low for this normal UK situation. When I mentioned this to the tech help line the operator got very defensive about the boiler and the fact it meets spec. I'm speculating here but the only reason I can imagine for a rapid change in his attitude when I started to talk about this is that they get a lot of calls about this model under-performing on hot water temperature. Certainly at some stage I would like to run a shower off the boiler and I have doubts about a nice high pressure toasty shower resulting from the current set up in winter.

I haven't done any measurements but water temperature goes up when the heating is on. Sometimes it is pleasingly piping hot, and sometimes it is just a bit hotter than the situation I describe above.

My current thought is that given that we are in the UK then UK products should accord with what I describe as the normal position above, mix hot and cold to get the right temperature (eg when I am at my girlfriend's flat, a bath is filled with about 2/3 hot water and 1/3 cold). If Worcester can't sort it out then they are selling a product that is unfit for purpose, and consumer law says that unfit for purpose products are returnable... Any thoughts about this please?

It seems to me that if the boilers are set up right (and we are getting a Worcester engineer here on Tues 23 Dec) that the one thing that we can explore is an infield upgrade to a greenstar 28i. That puts in an extra 12.5% (=1/6) and using a rough calculation, that should raise the water temperature by about 3 or 4 degrees. still not very good in my eyes.

Admittedly I am used to my old boiler where the water came out the hot tap scaldingly hot. Any thoughts here too please?

thanks
mark

You are still thinking of old systems with stored hot water.

Combi boilers are not allowed to give DHW much over 50° because of the risk of scalding.

If you want it hotter you have to reduce the flow. You dont seem to understand the relationship.

Combi boilers are best for showers and take a long time to fill baths.

If you have to use a bath then fill at the useage temperature.

Things move on! Safety is now paramount and risks of scolding have altered the world that you live in.

Tony

the rule that should be applied is: you get what you pay for.
apart from the junior 24i, you have got the smallest, cheapest and least powerful boiler that wb bring on the market; why do you expect a top performance?
the wb boys you spoke to are absolutely right to point out the boiler is working up to spec.
just hope that your 24i is an exception to my experience with these models.

Agile said:

You are still thinking of old systems with stored hot water.

Combi boilers are not allowed to give DHW much over 50° because of the risk of scalding.

If you want it hotter you have to reduce the flow. You dont seem to understand the relationship.

Combi boilers are best for showers and take a long time to fill baths.

If you have to use a bath then fill at the usage temperature.



Things move on! Safety is now paramount and risks of scolding have altered the world that you live in.

Tony

Click to expand...

Interesting, my Vaillant ecoTEC+ 937 is capable of delivering hot water at up to 65 degrees. Although we have it set at 50 degrees it can be very hot if set at 65 degrees which we tried when it was new.

The manual has clear warnings of very hot water especially if the legionaries protection has been activated.

Is this because it's a storage combi boiler?

David937 said:

Agile said:

You are still thinking of old systems with stored hot water.

Combi boilers are not allowed to give DHW much over 50° because of the risk of scalding.

If you want it hotter you have to reduce the flow. You dont seem to understand the relationship.

Combi boilers are best for showers and take a long time to fill baths.

If you have to use a bath then fill at the usage temperature.




Things move on! Safety is now paramount and risks of scolding have altered the world that you live in.

Tony

Click to expand...

Interesting, my Vaillant ecoTEC+ 937 is capable of delivering hot water at up to 65 degrees. Although we have it set at 50 degrees it can be very hot if set at 65 degrees which we tried when it was new.

The manual has clear warnings of very hot water especially if the legionaries protection has been activated.

Is this because it's a storage combi boiler?

Click to expand...

it's because you have 37kw (opposed to 24) and a storage tank both of which cost more to manufacture. A one litre vauxhall corsa will not give you the performance of a bugatti veyron-in other words you get what you pay for!

Hi,

Try running your tap slower. Are you saying the installer has checked the flow rate at 9ltrs/min?

Has he checked the gas rate of the appliance?

Sam

dangermouse46 said:

David937 said:

Agile said:

You are still thinking of old systems with stored hot water.

Combi boilers are not allowed to give DHW much over 50° because of the risk of scalding.

If you want it hotter you have to reduce the flow. You dont seem to understand the relationship.

Combi boilers are best for showers and take a long time to fill baths.

If you have to use a bath then fill at the usage temperature.




Things move on! Safety is now paramount and risks of scolding have altered the world that you live in.

Tony

Click to expand...

Interesting, my Vaillant ecoTEC+ 937 is capable of delivering hot water at up to 65 degrees. Although we have it set at 50 degrees it can be very hot if set at 65 degrees which we tried when it was new.

The manual has clear warnings of very hot water especially if the legionaries protection has been activated.

Is this because it's a storage combi boiler?

Click to expand...

it's because you have 37kw (opposed to 24) and a storage tank both of which cost more to manufacture. A one litre vauxhall corsa will not give you the performance of a bugatti veyron-in other words you get what you pay for!

Click to expand...

True

i have found alot of engineers are undersizing the gas pipe to these boilers. gas rating it would find out. not enough gas to it will lower the KW