boiler choice Vaillant Ecotec 937 or Viessmann 222F

[jockmonkey]

Help

well confused about boiler choice, different people telling me different things and really need some clarity..

Ok, background is, we are replacing an old Myson boiler, with a gravity fed tank set up. Works fine, but 18yr old and as inefficient as the hills.

Have a relatively big modern 4 bed detached. 2 showers 1 bath, kitchen with d/w & w/m. Plus 3 loo's. 4 people max occupancy but very little overlap in showering, and very very rarely baths.

Now, I understand both of these are reasonable top end boilers, looking at around the 35kW sizes.. both with some level of water store. So should give us enough hot water and hopefully enough pressure.

What we don't know is the Vaillant enough? Its way cheaper than the Viessmann but they ain't like for like. As the 222F has a huge store compared to the Vaillant.

Size of the boilers isn't an issue. Its got plenty of room to go in.

Any comments or feedback on either of these would be appreciated, as my head is starting to hurt.
I don't want to look at other makes. It's between these two.

Answers on a postcard please

Confused of Manchester

 

[weargas]

the vaillant is wall mounted so the weight of water it can hold in store has to be limited. It will look like a washing machine hanging on the wall. The viessmann is floor mounted so has a bigger store. They do a 222w which is wall mounted but it's only on the continent so far. Personally I think Viessmann.

 

[jockmonkey]

Will the Vaillant give enough hot water and decent pressure though...?

 

[Agile]

The 937 will give a flow rate of 20 li/min but ONLY until the store is depleted after a very few minutes. Its fine for filling a bath. Then it reverts to the basic flow rate of about 14 li/min.

The Viessmann is a completely different system and stores a lot of water and gives a very good performance.

It would be cheaper to have a seperate heat only boiler and unvented cylinder and still have the same performance.

ALL these possibilities need a very good mains water dynamic flow rate. Do a search on thet and look in the FAQ.

Tony

 

[CharteredEngineer]

Viessmann floats my boat.

However as Agile says, a large unvented cylinder coupled with a decent system (heat only) boiler will do the business.

You could get a combi and an unvented cylinder as well but its not a common setup.

 

[mickyg]

The 937 will give a flow rate of 20 li/min but ONLY until the store is depleted after a very few minutes.

you mean 10 minutes. Thats 200litres of water. Sufficient for most people for showering and bathing. Both are good boilers but the correct facts are useful for comparison

 

[Biggles..]

Why in this day and age would you fit a heat only boiler, ov is not the way forward.

Both boilers and unvented are pointless if the cold main can't deliver the goods

 

[Agile]

you mean 10 minutes. Thats 200litres of water.

Sufficient for most people for showering and bathing. Both are good boilers but the correct facts are useful for comparison

No, I dont mean 10 minutes! It will vary according to the operating conditions. Even the manufacturers dont dare quote how long it might give 20 li/min

Can you advise all the conditions that you have in mind when it could give 20 li/min for 10 minutes including how you think it will achieve that flow rate?

I certainly like showers for about 18-22 minutes! That seems quite common to me in owner occupied London properties.

Tony

 

[Biggles..]

Well I thought vaillant clearly state 200 litres in 10minutes where it then reverts to a standard 837 performance whilst recharging for roughly 5 minutes

 

[jockmonkey]

Does a non combi boiler give as good efficiency??

Never see the point of heating all that water just for it to sit and cool down again..I accept that the stores in the back of these boilers do just that, but with smaller volumes of water.

So, to sum up is it looking like most people would go down the viessmann route?

Should I assess the cold water pressure first? If so how??

 

[mickyg]

No, I dont mean 10 minutes! It will vary according to the operating conditions. Even the manufacturers dont dare quote how long it might give 20 li/min

yes they do, its in black and white in the product brochure.

Can you advise all the conditions that you have in mind when it could give 20 li/min for 10 minutes including how you think it will achieve that flow rate?

The conditions are the boiler being on and the tap being open.

I certainly like showers for about 18-22 minutes! That seems quite common to me in owner occupied London properties.

I think we all know thats bull. unless you've never actually timed it your in a minority. The average time for showering is 7-10mins. If you are in there for 20mins I don't want to imagine why and I also hope your on a water meter.