Central Heating/Hot Water Replacement

[jonnydarcy]

Hi,
I'm hoping someone might be able to offer some central heating/hot water advice.

I've recently moved into a new house with my wife and 1yo boy. It's an 1870s terraced property in Stoke Newington (London). The central heating system we currently have is 20+ years old and in need of replacement.

The house is big and pretty poorly insulated (although we're about to repair/replace/upgrade all the windows). It's split level but generally can be considered to cover 3-4 floors. All the rooms are large with high ceilings. E.g. 17 ft x 15ft with 12ft high ceilings. There are 5 bedrooms and all have radiators (some single, some double, a couple with thermostats, most as old as the heating system). Our current boiler is an open vented stored hot water system. It seems to work ok but is outdated.

We'll definitely stay in the house for at least 5-7 years and likely much longer (10-20). We're hoping to have another nipper or two over the next 3-4 years but definitely no more than that. So we'd probably end up being a 4-5 person family. Next year we plan to extend the existing kitchen (which is relatively small) into a large open plan kitchen/diner (25ft x 20ft) where we'd spend much of our time. It's also worth noting that if ever we wanted to we could develop the loft which we'd likely convert to a large bedroom or studio with en suite.

My question is, given all this information what kind of system should we look to install to meet our likely needs? For example, I have friends with similar properties who are use systems like Megaflow. Are these recommended?

All advice and ideas much appreciated.

Thanks

JD

 

[Chas12431]

An unvented hot water system is a good system and more suited to your property than a combi due to the house size and the amount of hot water draw offs that you could have

 

[gas_man_gaz]

if theres enough in the budget id also go for a unvented with a worcester ri boiler

 

[jonnydarcy]

ah ok, such as megaflow presumably?

Thanks

 

[jonnydarcy]

Just reading about thermal stores. They seem to potentially be the best system to install (no pressure build up risk). Are there any drawbacks or trade offs with the unvented mains pressure solutions?) Expensive perhaps?

Thanks in advance.

 

[jonnydarcy]

No-one with any view?

 

[JohnD]

when you fill a bucket at the kitchen cold tap, and time it, how many litres per minute do you get?

has the old lead pipe been replaced all the way to the pavement? Can you see the stop cock in your front garden next to where the gate used to be before somebody paved over it?

 

[jonnydarcy]

Hi, not timed but I'd estimate at full speed I'd get a litre every 3-4 seconds. 15-20 l/min therefore. Mains pressure is powerful I would say. I'll time it tonight.

Not sure about the lead pipe. The internal stop cock looks fairly old if that's any indication. Will take a look for the external stop cock. We have gravel rather than any paving so should be fairly easy to find if it's there.

 

[Agile]

You really need a dynamic flow rate measurement.

About 20 litres per minute @ 1.0 Bar is about the minimum for a mains powered unvented cylinder or combi boiler if you want reasonable performance.

Open pipe measurements give an indication but are not whats really needed. Its also very relevant how many hot water outlets you plan to have.

I would be reluctant to advise an unvented cylinder with just 15-20 li/min on an open pipe!

Tony

 

[jonnydarcy]

Thanks Tony. Ok I'll get a more accurate reading tonight. We live in a 5 bedroom house which fairly soon will have 3 bathrooms. However we're only currently a family of 3 and are very unlikely to be a family of more than 4 so 3 bathrooms might be a little misleading in terms of use.

 

[jonnydarcy]

I'm pleased to report pressure of 3+ bar and water flow of 25+ litres per min