On Fri, 11 Jan 2008 17:57:11 +0000 someone who may be Rob wrote this:-
Sounds like gravity circulation. Such systems have few advantages and are no more representative of current storage systems than a
1960s car is representative of modern cars.
There is also heat loss from the little under insulated cylinder in many combination boilers. A cylinder with standard thickness insulation is noticeably warm to the touch, one with double or more thickness of insulation is not noticeably warm to the touch but rather feels almost at the air temperature. There is some heat loss, but it will retain most of its heat overnight, dropping by 5-10C at most.
They are often combined in one product. However 'servicing'/'maintence' is slighlty misleading as it is usually only an 'inspection' for 1) safety and 2) to check if it can be insured. To me at least 'servicing' would involve, e.g. replacement of some consumable items, or adjustment/tuning to optimum performance. I might expect an annual 'service' would include checking/adding corrosion inhibitor but this is not the case, yet any failure due to lack of such maintenance is specifically excluded.. it's like taking your car to a dealer for a service and they refuse to change the oil and the warranty then does not cover you because the engine siezes up..!
And still are..especially those that scald children to death because a simple theromsostat failed.
..and unvented cylinder can do this:
formatting link
> I don't think there's a compelling
Ed at times you do prattle tripe!!!! A combi is a boiler that requires a once a year service....like every other boiler and no extra care whatsoever. Like any other product, buy a cheap one and they break down, buy a good one and the don't. Look at an Atmos.
Conventional systems are still the same. Talked to a lady last week who paid £150 because the oveflow from the roof was leaking. A £4 ball c*ck replaced and the man was there 20 minutes. Or your kids could scald to death if an immersion stat fails.
A wall mounted high flow combi like the Vaillant 937, Alpha CD50, Mikrofill Ethos 54C, etc work superbly. The Ethos even has a DHW secondary circulation pump kit so "instant" DHW at all taps.
A relative has a 14 year old Worcester combi - so old it had a bubble DHW heat exchanger. Last year it was leaking and the pressure vessel deflated. I fixed it and serviced. It had not had a service since new. It is still going strong.
In short having a metal cold water storage tank!!! Better have a "failsafe" system like an integrated metal F&E tank and cylidner thermals store or heat bank. Then no boiling water pouring down on children.
Until you claim and they see they have to pay out money, and then they look at the fine print and servicing history, etc. Insurance companies are not charities.
Look at the Ethos combi, they are highly cost effective.
formatting link
actually gives 23 litres/min @ 35C temp rise, capable of supplying two bathrooms. It takes an OpenTherm room temp controller. The Honeywell Cronotherm will do. It modulates the burner via the controller.
It also keeps the DHW heat exchanger warm too (user selectable). The DHW heat exchanger is a coil of copper pipe with three small pipes inside that. The temperature sensors just clip on the pipes in he boiler, so easily serviced as no drain downs. It also has an outside weather sensor as well.
They sell between £1,200 and £1,300 inc' delivery plus VAT. They are cheap for what they are. A floor mounted W-Bosch Highflow 440 goes for £1,550 and drops off in flowrate when the store is depleted. The Ethos 54C is an infinitely continuous combi - never runs out of DHW and the flowrate never drops too. Great for body jet showers, where many have to spend a fortune upgrading cylinder sizes when fitting them as they run of water quickly. These never run out of hot water.
Designed in the UK, and made in Holland. They use a Gionani heat exchanger, Grundfos pump and Honeywell 3-way valve. It is a commercial boiler downsized for domestic. The case is small too for the output. It is not like the Vaillant ecoTEC937, which is the size of a washing machine on the wall. This along with the MAN Micromat (ECO-Hometec) are about the best high flowrate infinitely continuous combis around.
You can fit a secondary DHW circulation loop with it giving "instant" DHW at the taps. They sell a kit, or make it up yourself using check valves and a bronze pump.
The only down side is that it only modulates down to just under 10kW.
If you want backup have an in-line instant electric heater. Switched off normally and the DHW to the kitchen sink and showers runs thought it. Switch on and temporary DHW at the showers and kitchen sink until boiler fixed.
A correctly installed plastic tank/cylinder with immersion can overboil and cold water tank collapse with the heat - an then more kids being scaled to death. There are superior failsafe water systems around, but the British think "you can't beat an old fashioned water system that dribbles out a shower ...,. and kills your kids too. How many have been close to death and they occupants have noticed a bubbling noise probably amounts to 100.000s.
This death was like pouring a large bucket of boiling water over your kid. Can't beat the old "conventional system eh!!!
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.