Condensing Boilers Are Rubbish!

Mankysteve

Azari wrote: »

Provided that your tank is well lagged, you will not lose much through having the water heating on all day even if you don't use the hot water as all you will lose is the energy required to replace the heat that has escaped from the tank.

And, provided the tank is not in the attic, that lost heat will be heating your house anyway.

There is no way that you are losing more through this than you are saving by having a condensing boiler.

Your getting condensing boilers and combi boiler mixed up I'm afriad. There two different things.

Condensing boiler just means the boiler sucks as much heat of your flue as possible.

What your thinking about is combi boiler that only heats the water as its needed

You can have a hot water tank with a condensing boiler such as the house I'm sat in right now.

So yes you do loose out by not at having condensing boiler.

Azari

Mankysteve wrote: »

Your getting condensing boilers and combi boiler mixed up I'm afriad. There two different things.

Condensing boiler just means the boiler sucks as much heat of your flue as possible.

What your thinking about is combi boiler that only heats the water as its needed

You can have a hot water tank with a condensing boiler such as the house I'm sat in right now.

No, it was the OP who had them mixed up.

That's why the post you quoted talks about a water tank separate from the boiler.

I assumed he had a non-combi condensing boiler - otherwise I would not have considered the possibility that there would be an external tank.

garethgas

I've explained to the OP that its how they are designed to work. His staggering and unprovoked arrogance in his reply to me suggests he's an only child.

mttylad

boozercruiseryou are completely wrong in your assumption that those links are JP's fault.

The fault lies with the installerof those combi boilers, had the condensate drain pipe been adequately sized, routed and lagged then the problem would not have happened.
Take a 20mm pipe outside unlagged and it can freeze, the boiler is designed to cutout when it cannot discharge its condensate. It should be 32mm when outside and/or lagged to prevent freezing.

You seem to be getting confused between a poor installation and the benefits of a condensing boiler.
My condensate pipe discharges inside the internal house drains and will never freeze like the links you gave.

As for turning hot water off when you have heating on, I think you will find that it is the same parts that are used to heat both so it is a natural side effect of having heating on to also have hot water.

When you did your research into your chosen boiler before you bought it, did you not find out how it worked? (What's that? you did not do any such research on a purchase of such an expense?).
The Worcester Greenstar Heatslave 18/25 is an extremely efficient system, it is 91%+ efficient which cannot easily be said for a lot of other types of system.

Just reading you explain the model allowed me to find the manual to find out how it works, or the specs on it just the same as I did before I bought mine.

It is likely that the only way you are going to not get it to not heat the hot water all day is to have it modified.

Consult a heating engineer about it rather than complain about JP in a completely unrelated issue.
(Jeez - you'd think JP went round doing shoddy boiler installs!)

lincroft1710

garethgas wrote: »

I've explained to the OP that its how they are designed to work. His staggering and unprovoked arrogance in his reply to me suggests he's an only child.

Even if he is, he hasn't insulted people who have siblings.

pineapple

I have a non condensing combi boiler. If we are truly talking about waste, well I can run a marathon and cook a 3 course meal (consecutively) in the time it takes hot water to reach the tap. Apparently they can use a lot of gas in the process. Also, since I like to rinse dishes in hot water, I have to keep the tap running till finished otherwise it goes cold and I have to start again. Good job I'm not on a water meter!
I now try to save up dishes for a once a day wash and boil a kettle if not having a shower in the morning.

Azari

pineapple wrote: »

I have a non condensing combi boiler. If we are truly talking about waste, well I can run a marathon and cook a 3 course meal (consecutively) in the time it takes hot water to reach the tap. Apparently they can use a lot of gas in the process. Also, since I like to rinse dishes in hot water, I have to keep the tap running till finished otherwise it goes cold and I have to start again. Good job I'm not on a water meter!
I now try to save up dishes for a once a day wash and boil a kettle if not having a shower in the morning.

Again, this isn't really a problem caused by having a combi. It's caused by your taps being a long way from the boiler (and possibly exacerbated by circuitous routing of the pipes.)

In some instances you might be better off with a hot water tank - if it would be nearer to the taps you use most - but this is not necessarily the case.

Avalo

I'm a heating engineer with 30 years experience and I fit mainly Vaillant boilers. A condensing boiler properly set up will, when in full condensing mode' be running at 97% plus efficiency. Most of them are now A rated and because of the the combined gas valve/ fan setup will throttle right back to tick over when the return temperature is nearly up to the flow temperature. This being said you need the right boiler for the right job. a worcester heat/store boiler in a small 1 bathroom property with not a lot oh hot water use maybe overkill but still should be a lot more efficient than older systems. You also need to have a good energy saving controls like a Honeywell CM927 RF programmable room thermostat and trv's that are set to the temperature you want in each room and not just fully open.

biscit

Avalo wrote: »

I'm a heating engineer with 30 years experience and I fit mainly Vaillant boilers. A condensing boiler properly set up will, when in full condensing mode' be running at 97% plus efficiency. Most of them are now A rated and because of the the combined gas valve/ fan setup will throttle right back to tick over when the return temperature is nearly up to the flow temperature. This being said you need the right boiler for the right job. a worcester heat/store boiler in a small 1 bathroom property with not a lot oh hot water use maybe overkill but still should be a lot more efficient than older systems. You also need to have a good energy saving controls like a Honeywell CM927 RF programmable room thermostat and trv's that are set to the temperature you want in each room and not just fully open.

Has anyone worked out what sort of system the OP has? Are we talking about the system where the water heated by the boiler is circulated through a heat exchanger in the water tank- basically a coiled "radiator" that was fitted to the tank at manufacture?

We had a combi in our house, but I remember way back and my grandad had a hot water tank. The system was fitted with servo-operated valves to shut off the hot water so that it could just heat the house if so desired. Are these still fitted? And/or are there TRV equivalents that could be fitted to a hot water tank?

ohblimey

The Greenstar Heatslave has a water tank inside it which is kept at a certain temp. If you use all the water in the tank the boiler then kicks in to become a combi, ie, it heats on demand so you have uninterupted hot water. So it is actually a combi, but not all the time. It's a very sophisticated piece of kit. That's why it's so efficient at just over 90%

With this type of boiler you really need a Honeywell timer which overides the boiler and stops the boiler heating up the water tank when you don't need it to, ie, just set the timer to come on in the morning for showers and then on again in the evening for washing up. If you need very hot water at any other time you just click the timer to the 'constant' mode, otherwise the water is 'just warm' which is fine just for rinsing hands.

The OP is correct in that it is wasteful if you do not have a programable timer to overide it, because without the timer the boiler is keeping the water hot all day.