Combi boiler Pre-Heat Function Whats best On or Off ? 

Great nice one, straight to the point, answered a few of my questions after sitting through loads of other videos, had a my 1st combi fitted last Wed, after watching this a few other of your other videos lots of useful info, thanks a lot.

We have the same boiler as you Al, and I always wondered what it was all about! Thanks for clarifying! As always, TFS 👍❤

👍After a boiler service from the housing executive my boiler kept coming on & i didn’t know why, I noticed that the preheat switch was on & didn’t know what it was for & was is better on/off, now I do & I’ll switch it to off. Thank you for the well explained video Al.👏❤️

Thank you so much for your video! I’m a new renter and have had it on since I’ve moved in about 4 months ago I didn’t know what it was for! You will save me a lot of money! I’m only in a small flat so the water doesn’t have a long way to go! Thanks so much!

Interesting video - thanks. Domestic properties in Scotland don't have water meters, so other than wasting resources, running water for a whole doesn't cost you anything. We switched off preheat because it costs more cash, but the alternative doesn't.

Cracked sumps, worn or broken flow turbine, leaking diverter valves & blown fans are amongst the few things you'll experience with ideal logics mini's and independent boilers. The pre-heats kind of pointless technology providing you have a decent water flow rate. It may be the case where your boiler's closely located to the supplying taps also again pointless using pre-heat. Great video as per usual Al 😊.

Just been checking my boiler and boiler manual. I can't seem to find an option for it. The thought of wasting money was giving me the sweats. Relax again now.

A great clear guide. Just the information I was trying to find. 👍

Thanks for the clip. Don't forget you're burning gas from the second you turn your hot tap on and there's only cold water coming through so if your your boiler is a long way off from the tap you would use most frequently you'll be burning a lot of £££'s over a short time. Even more so if the tap is used often but with long periods of time between usage. That's because the hot water you paid to heat which remains in the boiler and pipework to the tap, cools down and the whole process starts all over again. But like the man says; it's pointless leaving this on when you're sleeping or away from home.

Bit late to the party but with pre heat is it a case of keeping the main heat exchanger warm and the plate heat exchanger warm and obviously the water within the plate heat exchanger warm although this would be a minimal volume. Thanks 👍🏻

Excellent video Al, thanks very much, sorted that one out for me👍⭐

it was switched on, and I didn't realise it, as it did not have a designated switch to turn it on and off, I used to wonder why I would keep hearing the boiler firing up when the heating was off, luckily I did fin d out about it eventually, and it was using a good amount of gas, on my Vaillant turbo max it is the temperature dial for the hot water, if you turn it all the way round the maximum that would activate the preheat, to turn it off you turn it right down to the minimum, then back up to a hot setting just don't turn it right round to the maximum.

Thanks pal...straight to the point...Nice one

Pre heat for most users is a useless function. I have the boiler hot water set (48c) so that when I turn it on to do the dishes the cold water (at first) gives just the right amount of mixture, when the water warms up, to do the dishes, in other words I don't fill the sink with the cold tap. I also find that when I turn the shower on, I have a few seconds to get out of my under knackers and then the shower is lovely and hot.

We have a WB Greenstar 30Si installed Jun2006 and service regularly. I was interested in preheat vs no preheat (ours has an eco button to switch this ) quite a while ago so did a few experiments. I also just did the experiments today as I lost the data from a few years ago but i remebered rouhly what it was) Basically with no other gas requirement on the system the preheat uses just .011 meters cubed of gas every firing, and in a 24hr period was 0.265 meters cubed reading above starting point. No hot water tap and no heating was on in the same period, no showers.. By my calc on our current tariff that's just 8p per day. If preheat is off , our kitchen sink hot water tap takes 45 seconds before giving out tepid water to start filling a washing up bowl and another 45s to half fill the bowl. I can't be doing with that all winter vs 8p per day so our preheat is on all of the time. I switch it off in the summer though - just for variety. I think the conclusion of the video poster is good. Learn about it , understand it , do your own experiments and you will be able to use it as you see fit but in my case at 8p per day on , I see no reason for nightmares about bills. Oh, the hot water dial was set at 4 on a 0 to 6 max scale and 4 is hot enough to have to take hands away from hot tap (once its giving out full temp) after about 5 seconds as it feels too hot.

Thank you for your nice explanation. We have got a power shower, which only works if the Pre-Heat function is on. I think it is odd. I'm trying to find out why the power shower doesn't work when the Pre-Heat function is off. Any idea?

Hi Al, …..Hope you don’t mind me asking your advice, but would appreciate your thoughts please. We have a bungalow with a Glow-worm 25c boiler installed in the well insulated loft ! and it obviously gets cold up there. Would turning the “eco” mode off, cause any problems with freezing etc ? My understanding is, the boiler remains at approx 50 degrees on eco ? Tia

When it gets to freezing temperatures tomorrow night, will we need the preheat on to stop the boiler from getting too cold overnight as the house gets so cold?

Thanks Al. Great tip as always. 👍

What a nice guy

Some combi boilers like the Ariston evo only keep the water hot for a max of 30 minutes, which is handy for morning shower / shave / etc...

I have a boiler combi which has been off some months due to renovtion works. I noticed pressure was at zero under boiler but white overflow pipe outside was leaking until i turned water off. What causes this?

Cheers very clear and informative 👍

How long does it take for your water to get hot with it off?

Well explained mate, Thankyou

hi have older boiler that is not show any of these on boiler how i can stop pre heat?

Brilliant, I was checking the boiler and turned it on, until now, and after been woken up in the night.

As we have metered water,the issue of water going down the plughole wasted has been on my mind.Wondered if a diverter has been invented which only allows water from tap once sufficiently heated?The cold water diverted to a storage tank for garden use for instance.Dragons Den here I come ! Lol

What could it be when preheat is turned on and boiler doesn't come on at all to heat water.

Is it the same thing as " comfort mode"

Legend

My preheats all the time can't turn it off. The boiler isn't a good one every 30mins

I have P on my ideal boiler what do I do?

Long winded still not sure??

Hi there I have one of these boiler systems and I’ve had off during the summer and now when I have turned it on some radiator is warm and some off . I have bled all of them and I am still not getting anywhere. Can anyone reading this message please help me . Thanks 😊

So why hasn't anybody invented a boiler which begins to heat a small reservoir of water inside as soon as a tap is turned on but only allows the water to flow to the tap once the temperature, say 50 degreesC? In other words, it does not begin to preheat until a tap is turned on and prevents the water from flowing until it has reached a set temperature. That way you save on gas because you're not keeping the reservoir heated all the time and you save on water because it is preheated before it starts to flow. Simples. Idea for you to set in motion Al.

i leave it off as i dont pay for my water fuck yorkshire water

We prefer to have it off.