In neeed of a new boiler

[ziggy_b]

Hi all,

It's my first post so please be gentle.

I've been around for a while but just never bothered to register. I must say some great info on this site and has been a great help.

OK now! , I'm getting an extension done on house and soon will need to purchase a new boiler. Been reading alot of posts on the 'vaillant ecotec 937', now my question is! will it be powerful enough to run the following:-

1. In total 15 radiators
2. two showers
3. one bath
4. two bathroom sinks
5. one kitchen sink
6. another shower but thats a future development in the basement.

Keep in mind that a couple of of the radiators are going to be in the attic and the boiler i am thinking of getting it fitted in the basement so therfore the boiler will have to pump all the way up from basement to the attic ( It's an old victorian house).

 

[ziggy_b]

Any one plEEEEEESE

 

[corgiman]

Thats a big question to ask on line

we would need to know the flow rate of the main, where the gas line is is it adequate and so on

that is probably why no one has answered as they just cannot say.

 

[ziggy_b]

I know that i have got a 25mm blue main pipe coming into the property, but how do you measure the pressure of main?.

Do i have to call someone in or can i do it my self?

 

[Durgo]

Yeah mate, I used to work with plumbers on exstensions - they calculate how many btus by cubic meterage in the property and you factor in things like construction type, ceiling heights, radiator sizes and positions (they can be half as efficient in funny shaped room or if unidealy positioned) and insulation...the plumbers on the firm doing the exstion and the qs would normaly deal with all that though.

Have to say that when I replaced my own combi, I just went for a big powerful one, then you can run it at its most effiecient (not at full tilt) thing last longer AND you always have power in reserve.

 

[ziggy_b]

actually mi builder is doing my shell of the extension only, I'll have to find my own plumbers etc.

Just got my heart set on this 'vaillant 937' but concerned if it is powerful enough to do all the above mentioned

 

[gas4you]

If the 937 won't cope, and it wont with more than 2 showers going at once, then no combi (domestic) will.

 

[ziggy_b]

Thanks Dave, i was just waiting for your post

I've been reading alot of your posts.

so is that a no no to the Vaillant 937

 

[ziggy_b]

so what kind of boiler do you recommend?

 

[DIYBaz]

System boiler and unvented hw?

 

[simond]

Assuming you are using the attic then you have no space for a storage tank?

Then the 937 or the unvented would be compromised by the incoming water supply.

The 937 gives out 20 litres hot water at 35 Delta T; in laymans terms this means you can expect around 16-17 litres per min at a useful temperature (Vaillants are usually set up to deliver 42C delta T).

An unvented cylinder can allow circa 50 litres hot water per minute, depending on model.

Assuming you use water on a 2:1 hot/cold ratio, if you were to invest in a 937 you would need to see a water flow rate into your property of 17 litres (hot) plus 8 litres (cold) - 25 litres in total.

If you have a water main capable of supplying in excess of 25 litres per minute, you will see a benefit in the unvented cylinder.

By my reckoning if you want to use all those appliances you will need at least 50 litres per min. But unless you are connected to a fire hydrant, you won't get this.

We can design a system for this kind of simultaneous use, but it would be commercial spec, expensive, and I suspect total overkill for a normal house.

 

[gas4you]

Forget the sinks and concentrate on the shower/bath usage.

Do you realisticly envisage using everything at once ?

If not then assuming your water flow and pressure are up to spec the 937 will be your best bet.

If you do want all to work together then I think as a normal domestic situation you are on a hiding for nothing

In terms of hot water supply you could ahve a 937 running the showers and an unvented cylinder running the bath and sinks, or vice versa.

But going back to Simons reply your main problem will be the incoming flow rate and pressure from the street.

It would not keep up with demand from all at once.