High flow rate combis

[EPH]

Just got a job doing a 4 storey house that's being completely renovated by a builder, the spec said 24KW system boiler and 300 litre unvented cylinder, which for them is about right.

Met up with the customer today and says he wants a combi as this is his holiday home therefore on arrival he wants instant hot water. He suggested a Glow Worm Ultrapower as his friend has one in another property, am I right in thinking this still has to heat up the stored water anyway otherwise it just works as a combi?

Wondering what all your thoughts are on possibilities, those Alpha Flowsmarts interest me.

[andyg0507]

vaillant 937

[EPH]

vaillant 937

Tell me why........

[andyg0507]

It is SEDBUK band A rated (SAP 2009), has a 2 year warranty and offers output of 37kW DHW - 28kW CH. All the major components are built in and the boiler and tank are separate for easier handling. There are a range of plug in control accessories including a weather compensator and wireless programmable room thermostats.
actoSTOR is a twin 7.5l stainless steel fully insulated storage tank which features the aquaSENSOR paddle with hall effect switch that detects the flow rate of hot water. The ecoTEC plus 937 features a fully modulating energy efficient pump with low power consumptions from 8 to 44W.

[andyg0507]

But dont use the vaillant controls

[Mike Jackson]

Assuming it's multiple bathrooms how about using a combi as a system boiler and plumbing the kitchen sink and one shower to the combi and the rest to the unvented.

[mike-c]

Assuming it's multiple bathrooms how about using a combi as a system boiler and plumbing the kitchen sink and one shower to the combi and the rest to the unvented.

Decent idea.

Congratulations on your 2000 post.

[EPH]

Assuming it's multiple bathrooms how about using a combi as a system boiler and plumbing the kitchen sink and one shower to the combi and the rest to the unvented.

Honestly never thought of that. There is an issue with draw off times where he wants the boiler fitted so if I could keep the cylinder as hoped I can install a secondary return.

Thanks for that.

[Roger Welton]

Viesman 222F would be my call, best of both worlds.

[moogwai]

I fitted a 937 a couple of months back and was impressed by it.....kinda suprised me how good it was on hw delivery with 2 showers running.

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[mike_s]

Doesn't the Vaillant 937 only spec 15 litres per minute on the hot water? Worcester highflow cdi 550 specs 25 litres per minute, it has a 50 litre hot water store, not sure what the performance is like after the store has ran out but I know a fair sized care home that has 2 of them and they're happy.

The last 2 customers I have had request highflow combi's I've sold them unvented systems. At least the Worcester highflow has a 22mm cold feed, I don't see the point in fitting high flow/storage combi's with 15mm main as surely that can't do 2 showers?

Did a 300 litre unvented today, they originally asked for a highflow. Had 2 power showers and the kitchen sink on downstairs all full on hot,wouldn't get that with any storage combi.

I know this isn't the point of the thread, some don't have the space for an unvented. Anyway I would look at the Worcester highflows if I was you as I think they wipe the floor with the competition.

[moogwai]

I did recommend going unvented but they wanted a combi and according to my weir gauge i was getting 21litres a min from it....struggled to hold the thing under the tap!

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