Electric boiler for dhw only

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Hi
Would this boiler be suitable to provide hot water for a 2 bed mid terraced house?

9kw boiler

Heating is via E7 storage heaters, current hot water is cold tank loft, immersion heater, hot water cylinder in bathroom airing cupboard.

There is one bathroom with bath tap & thermostatic mixer shower + basin and mixer tap in kitchen downstairs.

Cheers
 
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I assuming your mains water pressure and flowrate is sufficient...
Why would you not choose an unvented cyclinder (or thermal store cylinder) instead (with dual immersions)...that would be the more normal solution.
That 9Kw boiler will require a dedicated wiring circuit at additional expense apart from the stooopid price.
 
First problem - Your incoming supply may not be able to support that 9Kw heater and your storage heaters in operation at the same time.

Second problem - That heater is intended to run a wet central heating system, do you have a wet CH system?

A typical 1.5Kw immersion heater will heat up a typical 120 L cylinder of hot water in around an hour, are you looking to speed this up with a 9Kw heater? It would need a circulation pump and use the indirect coil in the cylinder.
 
Cut a long story short... the wife doesn't like the immersion heater/tank idea as she runs out of hot water showering/washing her hair. Plus she wants to free up the cupboard space that the hot cylinder is taking up.

We have a 3kw immersion that runs for an hour in the mornings then half hour here and there to too up throughout day (think it's a 190l cylinder).

Regarding pressure & flow rate, yes would need to get that tested before committing to any changes.

Its only a small house, so heating wise there is one storage heater in living room, that's rated at 3.4kw, then a wall mounted oil filled rad in bedroom (2kw) plus a second in spare bedroom. That's it, we find the storage heater does a good job of providing most of our heating needs.

Basically she wants hot water on demand, with no bulky storage tank (there's no requirement for hot water for heating).
 
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You still would need a hot water cylinder and a header tank / expansion vessel with a this unit.

The C900 is designated as a 'boiler' and it will heat up the stored water in a hot water cylinder, exactly as a gas / oil boiler would, it can't be connected directly to the taps. OK at 9kW it will be 30% faster to heat it up than two 3kW immersion heaters, but costs 700% more to buy (excluding installation)

You are running out of hot water because you don't have the immersion heater on during the day. The same would be the case with an electric boiler. You can't have your cake and eat it.
 
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We have a 3kw immersion that runs for an hour in the mornings then half hour here and there to too up throughout day (think it's a 190l cylinder)

190 litres is about two bathfuls. If you run out of hot water it's because you haven't heated it all.

An immersion heater warms water at the rate of about 1 litre per minute. So an hour is not enough. Turn it on for three hours or more. Once it is up to temperature, the thermostat will turn off the power and it will use no more electricity until you use some of the hot water. You say you have E7 electric tariff so fully heat it overnight at the cheap rate, every night.

what colour is your cylinder?
 
Ok thanks. Are there combi options for hot water that doesn't require a tank?

Current hot cylinder is copper, clad in green insulating foam with an insulation jacket over top. I'll change the times on it so it comes on 1am-7am abs see if that makes a difference to amount of hw available.
 
Yes search for instantaneous water heater. There's an example here. I've never used one so can't comment on how good / not good they are. Probably OK for a shower, but will be slow for filling a bath. They require a large electricity supply, but will only use power when water is actually being used.
 
I would help if you specified the rise in temperature as well as the kW rating.

only if you want to check the calculation (which I'm sure you've already done) and quibble over the precision of my "about".
 
Once it is up to temperature, the thermostat will turn off the power and it will use no more electricity until you use some of the hot water.

It will use a little power if left on, even if no HW is consumed - just to make up for heat lost through the insulation.

I agree 190 L/ 3Kw will need much longer than an hour to bring itself up to temperature, but if the OP intends adding the 9Kw unit to the off peak load with the storage heaters, he will likely need to consult the DNO first.
 
cunningly avoiding my figure of 1 litre in 1 minute by 3kW.

BTW the average temperature of UK watermains is 7.3C. Warmer in summer, cooler in winter.
 

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