boiler Advice

cyclonebri1

diywhynot wrote: »

Some RGIs won't put the effort into doing a proper calc. We don't get deals from any manufacturer but make a recommendation based on what is the best fit for the customer/property as well as our experience with the product (I can't speak for others.;))

Then you are 1 of the good guys;);)
I think the principle stands in all aspects of consumer purchase, ask around and don't take any single advice/opinion as gospel.

Perry525

paulmapp8306 wrote: »

My installer is RGI registered, and said and, an either make is fine.

When I do a search for which boiler on various boiler manufacturer sites, they all point to a 28Kw or 30Kw boiler.

Its a 4 bed house with 17.5Kw worth of radiators, a 120 Ltr tank, one bathroom and one en-suit with shower, a kitchen and a UT room both with sinks. I would potentially need two sinks, a bath and a shower plus the heating on at one one time.

The current 18KW boiler struggles as it is. the heating water is getting cool by the time it hits the last radiator if there all on full on and theres three bigger ones to go in. I suspect a 24kw boiler may be enough, only just. no ro0m for any further expansion if needed and might struggle on a really cold day. 28Kw would be better but I cant find any decent makes (that i know of) that do 28Kw system boilers. Only Glo-Worm from what Ive found.

Both Worcester and valiant dont do 28Kw from what I can see. That said i might be wrong, hence wanting some advice.


that said, ive only looked at system boilers, not standard open vented ones (which the current on is, and which would work with a sealed system). Im also a firm believer of "too large rather than too small". Obviously from an economic POV there is a little saving in using something thats not too big, but i dont think (from a GAS useage perspective) theres much in it when using a sllightly too big boiler (as long as its not massively big).

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Are you one of these people who turn their heating off or down?
Keeping the heating on 24/365 keeps the home comfortable and means the boiler is only replacing heat lost.
If you turn the boiler off at night or when you go out, it will spend all its time trying to catch up.
Do you have a zoned system? Most people like to have bedrooms that are cool at night, are the bedrooms in use during the day?
Do you have thermostat valves on all radiators?

While your boiler may be old and it may use more gas to deliver a given amount of heat, you may like to consider that the rating given to a particular boiler is never checked and it is based on design only.

Modern boilers are sold on the basis of economy, with their performance enhanced by heat recovery from flu gases. This recovery only works during start up, once the system is up to speed there is little or no heat recovery and boilers old and new become much the same.

If you take the amount of gas used over the last 365 days with your current boiler, compare it with the presumed amount of gas used with the new boiler of your choice, establish the difference and do the maths, you will probably find the replacement will never pay for itself.

Better to stick with the existing boiler until it dies. I fitted the boiler in my last house 35 years ago, in the time I used it over 28 years (on 24 hours a day 365 day a year), I had to replace the thermocouple, that was the only thing that ever went wrong with it.

Have you considered the amount of heat lost through poor insulation?
Improving insulation levels will be cheaper and the effect will last for the life of the building.

cyclonebri1

Perry525 wrote: »

+++++++++++++++++++++++++++++++++++++++++++++++
Are you one of these people who turn their heating off or down?
Keeping the heating on 24/365 keeps the home comfortable and means the boiler is only replacing heat lost.
If you turn the boiler off at night or when you go out, it will spend all its time trying to catch up.
Do you have a zoned system? Most people like to have bedrooms that are cool at night, are the bedrooms in use during the day?
Do you have thermostat valves on all radiators?

While your boiler may be old and it may use more gas to deliver a given amount of heat, you may like to consider that the rating given to a particular boiler is never checked and it is based on design only.

Modern boilers are sold on the basis of economy, with their performance enhanced by heat recovery from flu gases. This recovery only works during start up, once the system is up to speed there is little or no heat recovery and boilers old and new become much the same.

If you take the amount of gas used over the last 365 days with your current boiler, compare it with the presumed amount of gas used with the new boiler of your choice, establish the difference and do the maths, you will probably find the replacement will never pay for itself.

Better to stick with the existing boiler until it dies. I fitted the boiler in my last house 35 years ago, in the time I used it over 28 years (on 24 hours a day 365 day a year), I had to replace the thermocouple, that was the only thing that ever went wrong with it.

Have you considered the amount of heat lost through poor insulation?
Improving insulation levels will be cheaper and the effect will last for the life of the building.

I'm sorry but your "theory" doesn't hold water and has been proven to waste energy hence money

paulmapp8306

True that. I do get the economy of replacing a boiler just for energy efficiency is usually bad financially. Taking an average £2500 for a new boiler fitted, with a 10-12 year lifespan (apparently for condensers - again if Im wring say so ) and a saving of £300 per year MAX, then its just about going to pay for itself over its whole lifetime. till in my case, its not JUST the age/efficiency, its the heat output not really being adequate, and the fact that if I change it now - when the other work is being done - its not going to cost anywhere near £2500.

I have done a whole house calculation, based on size of house, window sizes, insulation, radiator outputs - and it says 20.1KW is what I need (though that allows 3Kw for the HW, so maybe an 18kw would. do if I manage the times the HW and CH are on) - Id rather be safe though).

Given my current one says 14.7KW Max heat output (as someone said earlier - not the 18Kw I thought which is its input) can see why its struggling. Based on the current radiators alone needing 15.8Kw if there all on full Im definately going to need a higher output one. I guess the 24 KW is fine though. 9Kw+ more than I have now and 3 Kw+ more than the calculations suggest I need.

Theres no circulation issue, thats been checked. My fitter is doing my kitchen and bathroom plumbing - and has already done one radiator for us. He's sub-contracting from our kitchen and were more than happy with the work we have seen, and costs. He will fit the new boiler for no extra charge as hes already booked to be with us for enough days to fit it in, and hes getting a daily labour rate from the main contractor. were having the flush already thats been quoted for, so we only have to pay for the boiler, flu, controls, chemicals and any pipework. Looks like being around £1500 all in which isnt bad for a new boiler fitted.