To pre-heat or not to pre-heat, that is the question

Joined
7 Feb 2006
Messages
139
Reaction score
1
Country
United Kingdom
New Glow worm Ultracom 30CXi combi. Came configured with DHW pre-heat enabled. I have disabled it, as surely this must use quite a lot of gas over a year? What do you think?
 
:idea: leave it on overnight and see how much the meter moves?
 
I think you'll waste a lot of water waiting for it to warm up.

The decision whether you waste water or gas is yours, thats why Glowworm allow you to turn preheat off.

Vaillant owners with Vaillant controllers can time their preheat function, best of both Worlds.
 
Thanks for the replies. In reality, a quick swill of the hands in the downstairs loo would probably not bring hot through even with pre-heat, due to the distance. With a shower or bath, the amount of water wasted in proportion to that used would be reatively little. All down to personal preference as you say.
 
Unless my customers have a long run before their hot tap I always recommend leaving pre-heat off.
 
After reading simond's reply, I read the main manual more closely and it is possible to set up a second channel on the programmer to time pre-heat (this is not stated in the users manual). I have set it for morning getting-up time only.
 
This is one of points. That makes the goverments policy look stupid that every house should have pilot free boilers and they should be condensing. What uses less gas a non condensing combi or a condensing combi with pre heat. Defeats the object a bit.. Same as heat store cylinders , constantly firing boiler to keep a lump of water hot, but it`s ok cause they are attached to a condensing boiler.

It`s also great as a non smoker that everyone goes out for a fag now, but they are standing under patio heaters and halogen lights which are nil efficient because of where they are fitted . And there must be hundred of thousands of them through the country
 
Good point namsag - to be honest I couldn't believe this pre-heat thing when I first came across it, for the reasons you mention
 
Doesn`t matter how intelligent it`s still heating a boiler that may not be used. And if it is used, is it fuel efficient or just for convenience
 
still heating a boiler that may not be used

Thats the clever bit - it won't 'cos it has learnt when water is used the most.

is it fuel efficient or just for convenience

Well both really. Less water and gas is wasted - and the customer gets the water (at the right temperature) sooner. Remember a cold Combi could take a good while to reach operating temperature - that water usually goes down the drain and the gas is out of the flue.

I grant you that its not for everyone though.
 
As you say Dan used the most, but its not always used it is still guessing. As for water/gas being wasted it all depends wether person is having a bath/shower etc how close taps are to point of use or being run full blast or slow etc etc.
 
After reading simond's reply, I read the main manual more closely and it is possible to set up a second channel on the programmer to time pre-heat (this is not stated in the users manual). I have set it for morning getting-up time only.

Hi,

Where did you read this?

Is this for the New Glow worm Ultracom 30CXi combi
 
Namsag wrote

Same as heat store cylinders , constantly firing boiler to keep a lump of water hot, but it`s ok cause they are attached to a condensing boiler.

No, its Ok because heat store cylinders rarely give trouble due to simplicity.
As to firing the boiler to keep the water constantly hot that is not the case.
In any case modern cylinders are well insulated and as such standing losses are low.
Your combi v's heat store cylinder argument with the combi being more efficient is a myth in my opinion.
A combi saves space and thats about it really. OOh and they deliver p@iss poor hot water flowrates.
 

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Back
Top