Storage combi boilers

[Gemma]

Hi, I'm looking for opinions on storage combi boilers - particularly the viessmann 111-w. We currently have a gravity fed system but the space where the cylinder is is needed for internal renovations. Would this be a good solution - ie better than a standard combi in terms of hot water provision? We do have space for the boiler itself (I understand it is larger than standard combis).

 

[Scott_D]

How many bathrooms do you have?
What’s your incoming flow and pressure?

 

[Gemma]

Mains was measured at 20lpm at the outside tap. Currently have one bathroom with shower over the bath (power shower - I understand this will have to go). Will be potentially adding an en suite in future but I expect the shower over the bath will become redundant if we do. Main requirements at the moment are to free up space where the cylinder is and to ensure we still get a decent (as in good pressure) hot shower over the bath. But I've never lived in a house with a combi before so I'm a bit concerned about all the negatives I've read (drop in pressure when a tap turned etc).

 

[Riley]

You will need static and dynamic pressure and flow this will ascertain If you have the capability when more than one outlet is open. If you have any ideals to run more than one good shower or a shower and the bath at the same time then I wouldn’t look at a combi

 

[Aire]

How many occupants does your house have and how likely will it be that multiple hot water outlets will be used?

 

[Old Account]

Have you got mains lead pipe?or is the mains pipe already upgraded?

 

[Aire]

Have you got mains lead pipe?or is the mains pipe already upgraded?

Or cast iron, they're a nightmare for furring up and reducing flow rates.

 

[Gemma]

I'm told the mains pipe is plastic?

 

[Riley]

Get it checked and get the additional water measurements otherwise you may get caught out

 

[Gemma]

Will do, thank you. Is a storage combi worth paying extra for over and above a standard combi assuming measurements ok?

 

[Gasmk1]

for me if you have the space for it yes they are about twice the size in in depth and slightly wider, also the viesmann has a great weather compensation system for the price of a sensor approx £35.00

 

[Gemma]

Space for the boiler is one thing we do have, the current boiler is in a deep cupboard over the stairs.

 

[townfanjon]

Gemma , you will not go wrong with a 111 , best storage combi out there .

 

[gmartine]

I'd read on a website's spec the 111-w was suitable for "low pressure" areas, how can that be? Here it is...

Viessmann Vitodens 111-W 35kW Storage Combination Boiler Natural Gas ErP | Boilers

 

[Old Account]

Or cast iron, they're a nightmare for furring up and reducing flow rates.

Cast iron? Never came across cast iron yet scary Rubbish though

 

[Aire]

Yeah I've came accross a few. My parents had an old cast iron main, furred up that bad they was getting around 9 - 10 litres a min of flow. New main put in and now getting 22, massive difference.

 

[Harvest Fields]

You may have answered this already, if so then sorry. What size house do you have and how many bathrooms/baths/showers?

 

[Gemma]

4 bed (but a small 4 bed, size of a usual 3 bed I’d say), one bathroom with shower over the bath, possibility of adding an en suite in future but I imagine everyone will want to use the ‘proper’ shower cubicle then and the shower over the bath will be more or less redundant.

 

[Harvest Fields]

You could fit a large combi but not ideal really. The veismann May be a better option as it has a much bigger store. Personally I would try and fit an unvented cylinder if you can find space somewhere.

 

[Gemma]

Thank you, I'm still trying to get my head around how the storage combi works to be honest. Once the inbuilt tank is depleted it switches to a 'normal' combi, but what if the water in the tank is not up to temp for some reason - it bypasses it? It's only a 46l tank but it says its the equivalent of a 150l unvented - is that because of mixing with cold water? Just trying to understand it.

 

[Harvest Fields]

Yes. Once the store if fully up to temp and you open a hot tap, it mixers on the way out to the desired temp. Once cold it shifts to combi mode. You will probably notice a slight drop in flow when this happens. Nothing will ever replace the flow of an unvented though.

 

[Gemma]

Is unvented cylinder in a loft a bad idea? I looked at horizontal ones but my plumber isn't keen on them.

 

[Harvest Fields]

Is unvented cylinder in a loft a bad idea? I looked at horizontal ones but my plumber isn't keen on them.

You can fit it anywhere you want to be honest. Every engineer has his/her preferences.

 

[Scott_D]

cylinder in the cupboard boiler in the loft?

 

[Harvest Fields]

cylinder in the cupboard boiler in the loft?

They need to utilise the cupboard for their upgrade works. Both in garage or loft maybe?