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Haddock
Joined: 24 Apr 2005
Posts: 81
Location: Marburg, Germany
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Treacodactyl
Downsizer Moderator
Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism
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JKLawrence
Joined: 14 Jan 2005
Posts: 14
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 Posted: Tue May 24, 05 8:34 pm Post subject: |
 
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We have an oil-fired condensing boilder from Ecohometec (Swiss) installed in 2001. It breaks down regularly (usually twice a year, now getting more frequent). It does seem to be remarkably fuel efficient, but its efficiencies are ruined by the number of days we have to switch to electric heating and hot water until the engineer can visit. And services are now inexcess of �200! The boiler gets clogged up and needs a proper clean each time to get it working again.
It may be that this is just a bad manufacturer, or it may be that condensing is inadvisable for oil - after all, there must be some reason why there are so few oil-fired condensing boilers on the market. There is no gas pipeline to our house, and no plans for one.
Reading the posts here, I feel even less certain what to do. I'm looking into wind and solar, but the former probably couldn't do our heat and hot water, and the latter isn't cost-effective. I'm also looking into replacing the boiler with a new one (all are condensing now) from a different manufacturer. I've considered getting a Rayburn, but I don't think it could do heating for the whole house. I've even thought about wood-burning stoves - but I rather doubt we could cope with that route.
What would you do in my shoes? |
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dougal
Joined: 15 Jan 2005
Posts: 7184
Location: South Kent
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| Posted: Tue May 24, 05 11:38 pm Post subject: |
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JKL - dunno what your situation is so hard to advise. BUT -
you say the boiler is "clogging up"
- if you mean the exhaust through the condenser/heat exchanger, I'd wonder if there might be a difference in spec between the oil you are using and what the manufacturer expects.
- but if its the burner jets that are clogging up, then it could be that something as simple as a better filter might be the answer...
I'd try and get accesss to the Swiss tech people, who would likely take it as a matter of pride that their product should work brilliantly. But you'll need to be able to explain *exactly* what the problem symptoms are.
As to alternatives (or more likely, compliments), solar hot water is the most economic and most generally accessible "renewable". But solar is unlikely to be sensible for *space* heating - maximum need occurs when solar availability is minimum.
If you have a wood fuel resource, that route would make sense. If you want a range, you can get one with a "backboiler".
If you already have underfloor heating pipes installed, AND a nearby patch of ground (oooh, bigger than a tennis court) that can be seriously 'dug over', (or a lot of water !), then a ground source heat pump can be economic against oil.
If you have an exposed site, and could get away with putting up a biggish wind turbine that too might pay off - but we are talking about a big one, say 5kw, rather than a single 1kw Windsave...
Now, the thing is that you don't have to "put all your eggs in one basket" - you can use something called a "thermal store" (basically a big super-insulated hot water tank) to tie together different heat sources - say solar, wind and wood, with oil being used for a "top up" only when necessary. And you could plan and design for the addition of, say, a backboiler on a range or woodburner at a later date. |
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dougal
Joined: 15 Jan 2005
Posts: 7184
Location: South Kent
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| Posted: Tue May 24, 05 11:42 pm Post subject: |
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| Treacodactyl wrote: |
| I was told by an installer the condesning boilers only run at their stated efficiency when running for long periods. So you are encouraged to leave 'em running which uses more enerygy. |
*Any* equipment will only deliver its best under optimum operating conditions!
But, make no mistake, a condensing boiler will *always* extract more heat from a given quantity of fuel than a non-condensing boiler.
The essence of a condenser is that it has an "after cooler" which extracts useful heat from the hot gas that a conventional boiler would waste.
Because of that, the exhaust gas is quite cool - rarely more than 60C, from a condenser. A conventional boilers exhaust can be as hot as a baker's oven - 200C. Hot exhaust = heat being wasted.
Its that simple.
But to get *even* better efficiency, condensing boilers have two more features: a gas valve that can be part open (rather than just 'on' or 'off') and a very simple microprocessor controller (we are talking less potent than a Sinclair ZX81, never mind a Spectrum). The controller looks at the temperatures of the inlet and outlet water and the exhaust, and adjusts the gas valve for best efficiency. In that way instead of running flat out for, say, 3 separate 10 minute periods in an hour, the condenser would indeed run continuously but at less than 'half throttle'! This does not "use more energy".
| Treacodactyl wrote: |
| I also thought their lifespan is a liitle unknown due to the condensate being corrosive. |
Sadly, early British condensers seem to have been made with too little respect for the condensate. And "the trade" would have you believe that still applies to all condensers - it ain't so. But it is the case that the best made products are unlikely to be the cheapest...
Personally, I'd be more worried about obsolescence because of inability to obtain replacement electronic parts than corrosion. |
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JKLawrence
Joined: 14 Jan 2005
Posts: 14
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| Posted: Wed May 25, 05 12:23 pm Post subject: |
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| dougal wrote: |
if its the burner jets that are clogging up, then it could be that something as simple as a better filter might be the answer...
I'd try and get accesss to the Swiss tech people |
Thanks for your reply, dougal. I'm not sure, but I think it's the burner jets. I confess I've only whinged to the engineers - I might try Ecohometec's UK MD first, and if that doesn't help, I'll try the parent company.
As to the alternatives you mention:
- yes, we do have a big lawn that could do for a heat pump - but we don't have underfloor heating (have thought about it)
- we are very exposed (avg windspeed over 6 m/s), with a possible location out of sight, so a large turbine is an option
- we have a small woodland, with good conditions for coppicing, so a woodburner would be practical
| Quote: |
| Now, the thing is that you don't have to "put all your eggs in one basket" - you can use something called a "thermal store" (basically a big super-insulated hot water tank) to tie together different heat sources - say solar, wind and wood, with oil being used for a "top up" only when necessary. And you could plan and design for the addition of, say, a backboiler on a range or woodburner at a later date. |
Sounds ideal for our situation, given that we have lots of options - but we don't have the resources to pursue them all at the same time. Do you know who in the southwest designs these sorts of systems? |
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tahir
Joined: 28 Oct 2004
Posts: 45670
Location: Essex
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dougal
Joined: 15 Jan 2005
Posts: 7184
Location: South Kent
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fonant
Joined: 01 Feb 2005
Posts: 24
Location: West Sussex
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| Posted: Sun Jul 03, 05 11:33 pm Post subject: |
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| dougal wrote: |
| But to get *even* better efficiency, condensing boilers have two more features: a gas valve that can be part open (rather than just 'on' or 'off') and a very simple microprocessor controller (we are talking less potent than a Sinclair ZX81, never mind a Spectrum). The controller looks at the temperatures of the inlet and outlet water and the exhaust, and adjusts the gas valve for best efficiency. |
Our new condensing gas boiler is fantastic! The variable heat input (it's a modulating boiler in tech-speak) means it starts at full whack, and then gradually slows its fan(*) as the water heats up, meaning the gas usage and heat input is always just right. In use this means it has power to spare, so the heating comes on nice and quick in the winter, but the boiler can make itself "smaller" once the house has warmed up!
A major plus point is seeing the steam coming from the boiler exhaust as you get back home from a cold walk in freezing weather - a very welcome sight 
(*) our boiler has a clever gas regulating system using a pressure regulator to get the gas at (or slightly below?) atmospheric pressure, and a venturi in the air feed to the burner fan. Very much like a carburettor in a car. Fan speed pulls in air, which then sucks in the right amount of gas. |
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