Which type of replacement boiler and storage tank?

[Oddbod1]

We're about to undertake a ground floor bedroom and disabled bathroom extension. Current house is a already a 4 bed semi with existing bathrooms. Total occupants at the moment is 5 adults and 2 babies but will later drop to 3/4 adults. We had our mains lead pipe replaced with the larger, blue plastic pipe back in 1995.

We currently have a combi condensing boiler feeding the whole house, 28kw I think. It is about 5-7 years old. The problem is we dont have too much space in the extension we are building and I would like to know what my options are in the following scenario (my parents are old and retired so dont have too much money to spend esp the extension costs):

1. Can we avoid having a mega flow storage tank due to the amount of space it requires and opt for a larger capacity combi that can supply a min of 2 bathrooms at the same time?

2. Someone told me there is a type of boiler that has a certain amount of water storage capacity built in, is this true and what is is called if true?

3. If we had to have a mega flow, Worcester Bosch tells me that it is possible to connect my existing combi to a mega flow, but some adaptions would be needed. Is this advisable if we can save some £1300-£1500 on a boiler? BTW the boiler will need to be resited as part of the extension works.

4. How much space should I allow for a megaflow?

Thanks.

 

[Dan Robinson]

Can we avoid having a mega flow storage tank due to the amount of space it requires

Yes your existing boiler is fine....

a larger capacity combi that can supply a min of 2 bathrooms at the same time?

..... As long as you sent expect to do this. No combi boiler will run multiple showers at an acceptable level.

Someone told me there is a type of boiler that has a certain amount of water storage capacity built in, is this true and what is is called if true

Becareful what "someone" says. Most someone's age clueless half wits. In This case they may be referring to a Viessmann 111 or 222. Average products IMO. But might meet your needs.

we had to have a mega flow, Worcester Bosch tells me that it is possible to connect my existing combi to a mega flow, but some adaptions would be needed. Is this advisable

It's easy enough to do. You could even just use the combi side for one shower or kitchen and have a smaller cylinder cut the rest of the house. Megaflow are over priced and over hyped. Joule are superior in almost every way and cheaper.

How much space should I allow for a megaflow?

an airing cupboard.

Champagne ideas, beer money springs to mind.

 

[PullerGas]

At a push an unvented cylinder can be sited on a 800x800mm footprint, but it needs careful planning.

 

[Oddbod1]

Could someone please confirm for me, if I have a Worcester Bosch 29CDi standard combi boiler and we have 2 bathrooms, and when one is having a shower and someone opens the tap downstairs, the water pressure in shower drops and little water comes out, would I still have the same problem with a boiler with a storage capacity built in? Like the Viesmann 111 for example?

We renewed our mains 20 years ago and have blue pipe (22mm or 25mm?), but given that both types of combis require a good pressure and flow rate to operate, I'm wondering if I would face the same problem with being able to run two showers at once? Would having a separate megaflow system result in a different outcome even though the mains water pressure is what is pushing the hot water of the megaflow?

 

[Agile]

A storage combi combination like the viessmann will give you a higher flow rate but not always high enough to run two showers well.

They are really more designed to fill a bath quickly.

But why are you fixated on having a new boiler?

As explained above, all you need is a new cylinder heated by your current boiler!

All depends on your mains supply dynamic flow rate but running to good showers together will depend on how the supply has been changed. If replaced with a 32 mm pipe that should be fine. 25 mm would; need testing.

Tony

 

[Oddbod1]

Several plumbers I have asked, have suggested it will not be the best setup and that by the time you spent on the adaptions to get a combi to work with a megaflow, it would be minimal saving against a new system boiler and megaflow. Does blue pipe represent only one size or could it be either of those two sizes?

 

[ServiceNumpty]

Oddbod, have you had the cold mains pressure and flow measured?

 

[mcmoby69]

As Mikecip said. Doesn't matter what boiler or cylinder you have, if the pipe into the property isn't big enough, the boiler/cylinder isn't going to work. Shared water mains etc etc.

You need to spec it properly.

 

[Oddbod1]

Havent had the mains pressure and flow measured for about 10 years. We have turned down the mains stopcock tap under the kitchen sink because it is too powerful.