Replacing CH and hot water systems - conflicting advice

[mikeduke]

I have recently bought a 1930's detached house and due to the age of the boiler/radiators/pipework I am looking to replace the entire CH and hot water system. There are currently only minimal radiators upstairs and a lot of the pipework is running over the skirting boards and not under the floor.

There is a currently an open vented system in place, with both header tanks and the hot water tank in a large cupboard upstairs, also containing all manner of lead pipe. The boiler is based in a downstairs toilet which also contains a shower (which is pretty nasty!).

I want to replace all of the piping/radiators/boilers in the house but would also like to install a new shower upstairs, preferably in the place that is currently occupied by the hot water/central heating system. Meaning that I need to either get a Combi to get rid of this or to move the tanks to a new location.

Further complicating the situation is the fact that at some point in the next five year we would like to look at putting a two storey extension on the side of the house. For the sake of this project we are assuming that we will get planning permission for the extension (and be able to afford it!). The extension would also include a shower in an En-Suite bedroom.

There are 10 radiators to be replaced in the house with a further four to be added in an extension.

I have had a number (6) of plumbers/CH experts round to quote, but my problem is that they all seem to slag off each others suggestions and come up with their own way to resolve the issues. I was wondering if anyone had any suggestions as to how I can select the best solution. The main two options are:

1) To get a high rated Combi boiler (Valiant or Worcestor Bosch) at around 42Kw.

2) Get a pressurised boiler and place the large tank in the same room as the boiler.

My issues with 1, is that I am concerned that it will not have enough pressure to power two showers at once. Is there an easy way to test this?

My issue with 2 is that I would need extra piping around the house and have to probably move the pressurised tank after a year (when I take the shower out of downstairs, as the tank would have to be in a temp position whilst this was taking place).

Thanks in advance if you made it this far.

 

[picasso]

did any of the 6 plumbers test the incoming mains pressure and flow and if they did what were the results ?

 

[mikeduke]

Frustratingly none of them did, of the ones who recommended a Combi they simply observed the mains pressure at the closest tap to the water main, which also happens to be under the boiler. I wish I had read more information on here beforehand but having had a Combi in London flats for a number of years I had discounted them before I was suprised by their recommendation.

Is is possible to easily test the flow myself?

 

[Agile]

You need a dynamic flow of about 20 li/min @ 1.0 Bar ideally.

See the FAQ on this site.

Tony

 

[Kevgas]

Have you looked at a storage combi ie Worcester bosch hiflow 440/550,Ideal istor,Potterton,Vaillant etc and Alpha do a wall mounted version cd50 they will give you a better flow rate than a standard combi as long as youre mains pressure is up to it.

 

[Agile]

But only until the store is depleted!

 

[Kevgas]

50 litres of water at 60c mixed with the cold at 20l/min How long do you want to stay in the shower ?

 

[linkyplumb]

If flow and pressures are OK, then go for an unvented cylinder and system boiler.

As already stated these tests are a must. The flow cup is the first thing out of the van, when quoting on a job like this

Graham