ENERGY MATTERS

[Tizer]

I'm glad we moved to an area with a gas supply - the price of domestic heating oil has shot up from 35p a litre in June to just over 42p now, a 20% rise.

[Stanley]

Smart move Tiz, and it will go higher as the producers manipulate supply against demand, they are all hard up and the Venezuelan situation isn't helping.

[Tizer]

Here we go...
`SSE and Npower in energy merger talks' LINK

[Stanley]

Does this mean that every energy provider in the UK would be owned off-shore? Remember Nye Bevan......

[Tizer]

"British Gas has lost 823,000 domestic customer accounts, nearly 6%, since the end of June. Owner Centrica said 150,000 of those accounts had switched to other providers, some of them because it raised prices in September. The news, unveiled in a warning about poor trading, sent Centrica shares tumbling by more than 15%. Centrica said operating profits would be "lower than expected" because of problems at both its UK and US arms." LINK

[Stanley]

My heart is not bleeding. Simplistic I know but all that interests me is whether the gas and leccy are there when I need them. I suspect I am part of a large silent body of customers.....

[Tizer]

In this house we have a gas-fired condensing boiler (not a combi) installed some years ago by the previous owner. It's going to be replaced by a combi soon but I'm curious to know - should a condensing boiler still put out steam in this cold weather? We've never had one and my simplistic view is that if it's a condensing model there should be no steam whereas this boiler puts a lot out especially when it fires up.

[Big Kev]

The flue gases from a condensing boiler are much cooler than a conventional boiler so any 'steam' will be more visible.

[plaques]

Not sure its a simple as that Kev. They all preheat the water but the more modern ones are more sophisticated that they will turn the wick down as the incoming water gets warmer. This is more efficient on the central heating circuit which is returning at a higher temperature. Less heat input therefore less condensate.

[Stanley]

One of the main things to ensure with a combi condensing boiler is that it is on the 'economy' setting. This means that on normal duty the gas supply to the burner is modulated at a lower level and it cuts down on the visible vapour. Even on that setting, hot water demand puts it in full flow mode and lots of vapour emerges. The modern boilers are very clever. I still don't understand how my boiler modulates gas flow according to the severity of the conditions. Very low settings when the temperature difference between indoors and outdoors is low. It also kicks the boiler pump up occasionally in summer to ensure the impeller doesn't get 'frozen' in its housing. Clever stuff!

[Pluggy]

The visible vapour from condensing boilers is good.

At some point, usually in cold weather, the water temperature in the system reaches a point where its no longer cool enough to condense (typically around 55C - hot to the touch) and the visible vapour plume will reduce. But at that point its efficiency reduces so its better for it to be condensing. Most of the moisture from combustion doesn't make it out of the exhaust vent, it turns to liquid water inside the boiler and finds its way out of the drain. If you don't want a visible plume, don't use a condensing gas boiler, its that simple.

Kev is right, the flue gas temperature is lower in a condensing boiler, and that's why it condenses. No deep magic, it condenses because its cooler, when the water temperature gets hot, its longer cool enough for the water in the flue gas to condense on the heat exchanger and then it doesn't condense. Its about efficiency, they've always known extracting more heat from the flue gas is good, but that causes condensation and because the condensate is acidic it rots the cast iron and/or copper heat exchangers in old school boilers so thats why old ones don't condense. Condensing boilers almost universally use stainless steel heat exchangers on the gas side, some have copper on the water side .

Modern boilers are getting clever and will reduce the amount of gas they consume. They usually have flow sensors in the water system and measure the water temperature coming in and going out of the boiler and many also have inlet air temperature sensors so they know how cold it is outside. If its mild the water doesn't get so hot because it doesn't need to. Keeps it condensing and therefore more efficient. If thermostatic radiator valves reduce the water flow, the gas modulator turns the gas down to stop the water temperature soaring. Damn clever stuff.

[Tizer]

It's amazing what you learn when you ask a question on OG. Thanks!

[Stanley]

One of the things I have noted about boilers of all sizes over the years, including the largest industrial ones is that the ones that gave the least trouble were those that were well on top of their job and were left alone to do their own thing. The worst were where a 'local expert' was constantly tuning them. That's why I have my heating on 24 X 7 X 365. The only modification I ever did to this was to cut a hole in the boiler casing so that I could see the water pressure gauge without opening the door. All I ever do is check that it is in the green sector. I have seen boilers ruined because of leaking relief valves......

[Pluggy]

For someone who wears 'pedant' as a badge of pride, shouldn't 'boiler' be 'calorifier' ?

[Stanley]

Technically correct Pluggy but 'calorifier' to me is a heat exchanger that heats hot water by passing steam through a nest of tubes....

[Stanley]

I was reviewing heating.... I haven't lit the stove yet as when I do it alters the heat distribution and starves the shed of heat. At the moment the kitchen is on 18C and the shed slightly less but comfortable when you are working. The front room is just below 20C and I sometimes feel the need for a light cardigan. The bathroom is over 20C as the door is closed all day and the boiler is in there. Bedroom slightly below 18C but that's OK I like it like that. The body of the house, hall, stairs and landing are where the thermostat is and at 18C. This makes for a comfortable house with no excessive heating and suits me. If we have harder weather I'll still consider starting the stove to have a toasty front room!

[Tizer]

The plumbers start work here tomorrow - new combi boiler, the very old rads replaced (that's most of them, including the biggest ones) and taking out the HW cylinder and the old loft cold water tank so that we're on mains pressure. We'll get rid of the noisy shower pump and also have mains water to all taps instead of just the kitchen one. Fortunately the ambient temperature has risen from last week's 5C to about 10C and will stay that way for the week.

[Stanley]

Handy Tiz, I'm glad for both of you. No wood burner in the new house then? Mind you, we have a hard frost this morning!

[Tizer]

Correct, no wood burner. We'd give up with it at the old house in the last couple of years, partly due to a change in the local weather patterns causing poor draught and partly because my compromised breathing means I have less energy to chop and saw logs and the dust puts me in coughing fits. Also we had plenty of free timber at the old house in the country and not here in the town. And now we have gas piped into the house and a gas fire in the lounge - luxury living! Even when bought by the ton, logs are now rated as about 65% more expensive per KWh than gas. That's because log burners have boomed in popularity, especially among the well off.

[Stanley]

Good thinking I reckon. I haven't used mine yet this winter but it's there as a stand-by!

[Tizer]

A floor level fitted cupboard in the kitchen of our `new' house always seemed to be warm and we suspected that one of the CH pipes must go through the gap behind it. I decided to explore today by unscrewing the back panel and pulling it out...and found Spaghetti Junction! Large bore pipes feed a manifold serving narrow bore pipes. These dive into the concrete floor to supply the ground floor rads. There's verdigris on the pipes but everything is bone dry. The CH must have been installed when the house was built in the 1970s.

[Pluggy]

It looks like the self same manifold I put in this house in around 1980 - 22mm large borem 10mm small bore. I've had no reason to change it in the intervening 37ish years.

[Stanley]

A masterpiece of the plumber's art! Remember that verdigris is poisonous......

[plaques]

I wouldn't like to unfasten one of the centre connections but at least you have plenty of flexible pipe to maneuver with. It must be a warm little cubbyhole there is no pipe insulation and the concrete floor will be nice and warm too. Sorry about that Tizer.

[Tizer]

No problem, Plaques. I'm going to put polystyrene sheet + reflective foil across the wall at the back behind the pipes and along the concrete floor then probably fill the rest of the cavity with mineral wool.