combination boiler advice please

[wobbly]

Hi all
after 7 years of my ariston genus i have had enough,more breakdowns than any car i have ever had and very expensive to run

i did the test for my required heat and it says 13.36kw which equates to 44,000 BTU which seems high
I live in a large 4 bed semi with an original (1922) loft conversion
I used to have a worcester bosch 28cdi in my old house which was an excellent boiler,the one problem that I had in 8 years WB came out for a fixed fee and repaired the pump in ten minutes flat

so i am erring towards WB

the only issue I had with the 28cdi was the flow rate for a shower was poor

what would you people recommend for a decent flow rate and a 4 bed house

many thanks in advance

tony

 

[Agile]

Before considering a combi over 24 kW you need to measure the dynamic flow rate.

I would never recommend a combi in a four bed house!

Tony

 

[Terry lambert]

Plus1

Worcester now do a 38 cdi which will give you more on your flow, if you have a decent incoming flow and pressure.

You need to get these measured first.

I also wouldn't recommend a combi for a four bed house, because they are designed for one tap operation.

 

[wobbly]

crikey i remember you from 4-5 years ago
I am still on paving expert and i guess you are still here
for various reasons (airing cupboard etc all long gone) we are pretty much stuck with a combi
the gas safe bloke at work (I am a builder) likes fitting valliants,but the WB customer service has stuck in my mind
do you reckon the greenstar 38 cdi would give a decent flow rate tony?
appreciate your help
tony

 

[Terry lambert]

Remember who?

 

[wobbly]

looks like we are thinking on similar lines terry
when i moved in i moled a new water main in ,not sure of the flow but in building terminology we have good pressure
the gas pipe from the meter is 22mm all the way
although the house is big there is only me, the missus, and 1 child,
at present there is no issue with showers etc clashing as I am out of the house early doors etc etc
paying over a ton a month gas bill at the moment and would like to reduce it
same as everyone i suppose
thanks for your suggestions
tony

 

[Terry lambert]

The 38 cdi lists a 16.4 litre a minute flow rate at a 35 degree temp rise, which means you will probably get about 13.5 - 14 because they have a flow restrictor anthem for a 42 degree temp rise.

Again if you have the incoming.

Your gas pipe might also need upgrading

 

[wobbly]

//www.diynot.com/forums/viewtopic.php?t=123622

I think the ariston has about 18 litres per minute,but the hot water holding vessel is so inefficient
I was talked into the ariston at the time due to the high flow rate so do not want to get caught out again
thanks fellas
tony

 

[Terry lambert]

A this big will need at least 28 mm depending on length which your installer should be able to calculate.

On an earlier threa someone I repect on here was recommending a glow worm storage combi, giving you 19 litres a minute, this might be worth looking at

Again without knowing your incoming main pressure and flow it's hard to comment,

You can only get out what you have coming in

 

[Terry lambert]

Take note that most of the combis have restrictors in them and will not give you the flow rates listed at a 35 degree temp rise

 

[Agile]

For anyone wondering, its traditional to quote the flow rate at a temp rise of 35 C for ease of comparisom. Thats fine in summer with 15 C incoming water.

BUT in cold weather the incoming can be 5 C or less. That would not give a hot enough supply as we like to shower at about 40-43 C an many like it hotter to add some cold water.

So to make people happy ( because they can be too stupid to reduce the flow rate at the tap ) the designers restrict the flow through the boiler!

Tony

 

[Terry lambert]

In my opinion it's misleading, customers do not know how they calculate the flow rate and performance, if it says 16.5 litrs min then that's what they expect.

 

[boilerdoktor]

whats this conversation about ?? WB are THE best boilers! get one !

 

[Agile]

Do you install over 50 Worcester boilers every year and wear a Worcester badged jacket?

Mine has become very tatty indeed and although warm and comfortable getting embarasing to wear. Not a very good advert for Worcester!

 

[wobbly]

i cant remember the flow rate of the old 28 cdi but you couldnt have the water too hot if you wanted a decent flow rate
the genus i believe is around 19 litres per minute at 30 degrees,and although it has a 60 litre tank i cant attest that my daughter has spent half an hour in there with it on as hot as you like
so the 38 cdi looks a winner
cheers fellas
tony