New Heating System Advise

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New Heating System Advice

Our ageing Worchester boiler has given up after 23 years of service, it needs a new expansion vessel but the burners have seen better days and are not burning cleanly it is currently hanging on in hot water mode only but needs replaced before we need heating.

I have struggled to get quotes contacting 7 local companies only 2 got back to me which has surprised me as I thought this would be a quieter time due to the warm weather, I am hoping to get a 3rd quote

Our current system is a Highflow 3.5 combi boiler that has an internal hot water tank. The system is flat out with both the hot water and heating running the burners at the rated maximum of 22.9kw and has always taken a while to heat the radiators, it can supply hot water to two taps/showers but once the internal tank is empty you notice the drop in temperature.

Of the two that have came back to me one has recommended converting the system to have a system boiler and an unvented hot water cylinder as he commented that the house would have a very high hot water demand (I knew this but he brought it up first), he fits Valliant, Worchester Bosch and his main brand is Ariston. I ideally wanted to fit a Valliant which he advises are good as they have a stainless steel heat exchanger but he was pushing me towards the Ariston systems which also have a stainless steel heat exchanger but would come with a 10 year warranty compared to 5 years for the Valliant. I was impressed with the chap doing the quote as he explained everything and seemed very knowledgeable.

The second company fit Worchester Bosch and Valliant, again he advised that the Valliant was good as it has a stainless steel heat exchanger which the Worchester doesn't he didn't really comment on hot water demand until I brought it up that I didn't want a large restrictor on the hot water as I like our high flow shower and has recommended to supply the ecoTEC plus storage combi which does have a 15l min hot water through put due to a small internal water tank similar to our old combi, the first company thought this boiler wouldn't quite be up to the task of filling a large bath then running two taps/showers quickly after.

In short are Ariston boilers any good ? and would my hot water demand need a cylinder or would a high powered combi do the job. We have 21-22L a minute water flow and good mains pressure, 3 baths, 2 mixer showers and will probably be adding another shower. Unlikely 3 would run at the same time but 2 is fairly common and my wife likes to have lots of baths.
 
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All installers want to fit unvented as they're more complicated and therefore bigger jobs / more money etc. That said, they are ****ing awesome as you get mains pressure hot and cold water at every outlet, and basically never run out of hot water as the worst you'll ever get is what your boiler can provide on-the-fly. The best you get is hundreds of litres of high pressure steaming hot water, instantly at every outlet.

On the other hand, a really good combi is fine for many many households and much cheaper than unvented. However the speed with which your wife's bath will fill would be slower if someone was running a tap, using another shower, etc. with a combi system.
 
Valiant ecoTEC plus 937 has a built in water storage tank.

Otherwise I would be looking towards a Megaflow type system, combined with a cheap valiant combi,as that gives mains pressure hot water.
 
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Valiant ecoTEC plus 937 has a built in water storage tank.

Yes that is the boiler the second company has recommended, I have asked the first to quote for this aswell. I am still waiting for the actual figures from both but the first company said fitting a cylinder would be around £5-600 more over a combi boiler as the price of the cylinder is offset by a cheaper system boiler.
 
Just had a vaillant 937 installed. Haven't had much experience with it yet as we are yet to get an ensuite installed, but the data sheet for the vaillant says 20 litres per min for 10 mins, then 15 litres per min after that.

Will be able to give a better impression of the 937 after spending a winter with it !
 
Just had a vaillant 937 installed. Haven't had much experience with it yet as we are yet to get an ensuite installed, but the data sheet for the vaillant says 20 litres per min for 10 mins, then 15 litres per min after that.

Will be able to give a better impression of the 937 after spending a winter with it !

Ahar: Will be interested in reading your feedback on Valiant 937.
 
I would deffo go with a system boiler, but a Worcester Greenstar 30Si (combi) should have the power to supply lovely hot water to the heating system and the taps on demand :) (means no need for the tank as well).
 
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