Worcester Greenstar 30i for a 4.5 bedroom 3 bathroom house?

[Rueben Derrick]

Hi

We current have a 10-year-old pressured HWS with a Potterton Supremo 80. The system leaks at the pressure value above the boiler and the PRV also leaks.

Our house has 4.5 bedrooms, 2 lounges, 2bathrooms and kitchen. With the possibility of a third bathroom going into the loft in the next 3 years. 11 radiators in total.

My friend who is a qualified plumber who fits gas boilers everyday is suggesting the 30i will create enough hot water while maintaining good pressure if 2 people are having a shower at the same time and the CH is on.

However, Worcester Bosch says that boiler is for a 2-3 bedroom house with 1 bathroom.

The old owner of my house who put in the pressured system says, yes its about years old and might need modernising but I'm mad to be considering a combi when I already have a Pressure HWS, and I should just update the boiler but keep the pipe work as is.

ADVICE PLEASE

Regards Rueben

 

[ShaunCorbs]

Sorry to say your friend is talking out his bum

Combi boilers will only run either heating or hot water, not both together

Also there only ment for one outlet use (unless your happy with 6lpm on each

Best way would be an unvented cylinder and heat only boiler, like you have

So my recommendation would be replace the main parts (boiler cylinder) with new ones and sort any leaks out

 

[Chuck]

I wouldn't consider a combi for a house of that size.

In any case, once you've had a pressurised hot water system in your life there's really no going back.

I love my Megaflo. Just love it.

 

[Rueben Derrick]

I wouldn't consider a combi for a house of that size.

In any case, once you've had a pressurised hot water system in your life there's really no going back.

I love my Megaflo. Just love it.

Hi Chuck

Where would I notice the issue if I downgraded to a combi if I'm coming from a Pressurised hot water?

Rueben

 

[ShaunCorbs]

Hi Chuck

Where would I notice the issue if I downgraded to a combi if I'm coming from a Pressurised hot water?

Rueben

Can't have more than one outlet open or both heating and hot water on

 

[Chriswareham]

there is nothing better than a pressured hot and cold water it takes up more space but worth it in my opinion (fitted with an accumulator that stores pressured cold water for areas with poor in coming main.)
maga flo needs 20lts per min and 1 and 1/2 bar of pressure but this needs to be re-energised from time to time to keep up the pressure.most people dont do this and the pressure depletes
in may opinion ariston duel streem are the best . no noisy pumps and grate pressure

 

[Chuck]

Where would I notice the issue if I downgraded to a combi if I'm coming from a Pressurised hot water?

If you only plan on using one shower or running one bath at a time you probably won't notice. But if you need three bathrooms you are likely to want to use at least two of them simultaneously and then the limited flow rate will become an issue.

A few estimates to illustrate:

If the incoming supply is at 15°C and you want water at 45°C then with a 30kW boiler you will be able to have ~13 litre / minute.

~13 litre / minute is plenty for a single 'good' shower, and is okay for two simultaneous showers but you'll want good quality low-flow heads set to deliver say 7 litre / minute. Three showers simultaneously? Not unless you like cold showers.

A traditional low pressure hot water tank with 3/4" pipework and BS5412 taps might fill a bath at say 32 litre / minute, that's two or three times the speed of the combi. A pressurised system might be five times as fast as the combi, depending on taps and pipework.

 

[king of pipes]

definitely stay with a pressurised cylinder and heat only boiler a combi is not suitable for a property your size regards kop

 

[Rueben Derrick]

Thank you so much for your advice.

Chuck thank you, I can get my head around your examples, much appreciated!

I now realise what's at stake and also realise I have been leaving something rather important out of the equation.

It's only my wife and me + 10-month-old in our house. Its unlikely my wife and I will shower at the same time as we get up at different times. Our son is bathed at nights until, I'm guessing 8 years old?

So for at least the first 8 years, we won't be showering at the same time and then if we do it will be only 2 showers in the morning...maybe.

Is it fair to say new boilers only last around 10 years? So even if we went with the 30i combi or the 30i system, both would need replacing in 10 years?

My plumber friend is also suggesting if we don't like the combi he would swap it out with a system and new cylinder and all we would pay if the priced different and extra labour, not the cost of a totally new boiler.

I have found the unvented system boiler we have, nothing but trouble (not to say if we renew all the bits it would behave itself). I'm attached to the simplicity of the combi and the added monthly cost savings, plus we are looking at using Honeywell's Ecohome as well.

I just scared, very scared I'm ignoring all this good advice foolishly and heading towards a combi and in 3 months time I'll be saying to myself "why did I listen to my friend".

R

 

[ShaunCorbs]

Go with a heat only boiler tbh there bullet proof if installed correctly