DIY Doctor UK DIY Forums

Hi,
My girlfriend has just bought a flat with an OSO 125 litre boiler.
There's no gas in the flat.
I'd appreciate some help please.

My girlfriend has said she was only getting hot water for 4/5 minutes and not enough to fill a bath. She had ony switched the immersion on for 20 minutes - is this the reason? (i.e. needs to be on longer)

I have just been on the OSO website. It is a direct system and I notice the it'll take approx 100 minutes to heat the water but the indirect version only takes 25 minutes. Why the difference? I can't see any answers on the OSO website. 100 minutes seems a hell of a long time?

I had grown up with the immersion heater as the very expesnive fall-back for heating water - that you never used unless absolutely had to. So with only an immersion I can't halp thinking it'll cost a mint to run?

I don't have raditators (or know if that is relevant anyway) - I have Nobo Series 14 E4En heaters (again - any views on these?).

Thanks in advance for any advice / info.

Hi, the difference is heating element size.
direct 14.4 kW 50% more than the largest shower, heated as used.
indirect type 3kW, not much bigger than a kettle!
kettle holds say 1 litre, takes 2 mins to boil, bath holds say 50 litres, do the maths, heater needs to be on at least an hour before a bath can be drawn.
It is usually cheaper to leave heater on 24/7 than try to heat from cold each time,
regards [all electric] SPARX

Thanks Sparx.
Excuse my ignorance here - but boilers are a black art to me. You mention it's better to leave it on all the time rather than heat from cold when needed.

I assume this is because it has a thermostat inside that ensures it does burn electricity constantly throughout the day - but just has low electricity need to maintain the temp.

Thanks in advance.

Hi again,
Most water heaters have high levels of insulation so once up to temp. the inbuilt thermostat will bring element back in circuit after a temp. drop of around 2deg.C and after a couple of minutes turn off again so taken over a 24hr period would only be on for maybe 30mins, about eqaul to or less than time to heat from cool & bonus is if in a hurry no waiting as water always ready. Obviously once a bath drawn there will be a longer 'on' period to get back up to temp. but still a saving.
We are all electric here and have tried all ways of operation over last 35 years, only way we can cut cost over above way is with the additional solar panels we fitted 3 years ago, my children may see the payback point where savings = outlay but I doubt I will!!!
regards SPARX

Great - many thanks for the help.
Regards.

[quote="sparx"]Hi again,
Most water heaters have high levels of insulation so once up to temp. the inbuilt thermostat will bring element back in circuit after a temp. drop of around 2deg.C and after a couple of minutes turn off again so taken over a 24hr period would only be on for maybe 30mins, about eqaul to or less than time to heat from cool & bonus is if in a hurry no waiting as water always ready. Obviously once a bath drawn there will be a longer 'on' period to get back up to temp. but still a saving.
We are all electric here and have tried all ways of operation over last 35 years, only way we can cut cost over above way is with the additional solar panels we fitted 3 years ago, my children may see the payback point where savings = outlay but I doubt I will!!!
regards SPARX[/quote]
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I too am all electric, storage heaters & 0ff peak Economy 7.
I've just had solar water heaters fitted, & am disappointed.
I am beginning to think that with hard water & without a boiler, it's unsuitable.
Is your calc of 50 Ltr bath right? mine's 210 Litre. (not bragging)

You have a direct cylinder heating the water directly - like a kettle.

An indirect cylinder is heated by a boiler situated somewhere else - indirectly.

You have two immersions.

The lower one will be wired into the Economy7 heating circuit - only runs between 11pm - 7am.

Leave it switched on all the time and you will have a full cylinder of hot water every morning. The electrics in the house will turn on and off automatically.

The higher immersion is a top up one - use if she has friends round and more hot water is required or a lot of laundry has been done throughout the day before a shower/ bath is required in the evening.

hth