New Gas Boiler

Slinky

matelodave said:

Unfortunately I can't persuade my wife to stop rinsing stuff, including her hands or even yoghurt pots without running off five litres down the drain and then leaving another five to sit in the plumbing to get cold until the next time.

With the costs of water, gas and electric, divorce could be a moneysaving option?

Magnitio

Section62 said:

Magnitio said:

Hot water cylinders will typically lose between 1 and 2 kWh of heat every day, even those that are very well insulated. At 7p per kWh, that's £25 to £50 per annum. There are also inefficiencies in heating that water from the boiler. Replacing an old 75% efficient boiler with a 90+% efficient boiler could easily save a further £200 a year for heating a typical house. With the increasing gas prices, the savings will be even greater. There is also a significant environmental benefit of using less gas, as well as political if we can reduce our imports.

But see victor2's post immediately before yours.  If a combi is not installed with the pipework optimised then there will be a volume of water wasted each time a hot tap is turned on when the water in the pipe has cooled.  If the property has a water meter (which more and more of us will have going forward) then you need to factor the cost of wasted water into the equation as well.

Rearranging the hot water distribution pipework to make it more efficient is an option, but it would be easy to spend 10 year's worth of energy savings (in the £25 to £50pa range) getting a plumber to do this.

And then when we are no longer able to buy gas combi boilers most of us will be looking at installing some form of hot water storage tank.  Again, for most the optimum place for that future hot water storage tank is likely to be where the existing or previous one is/was.  Necessitating another reorganisation of the hot water distribution system if it has been altered to suit a combi.

There are many factors other than the current price of gas which need to be taken into consideration.  Personally, I would increase the insulation on the hot water cylinder, and otherwise make the minimum alterations necessary until there's a clearer picture of what future domestic heating is going to consist of.

My MIL's boiler and hot water cylinder were replaced with a combi that fitted in the airing cupboard in place of the cylinder. Both were 25+ years old and inefficient. The length of pipes from boiler to taps were the same. Being quite old and therefore a high gas user, savings were significant enough to provide an ROI of 5 years.

There is no point in generalising, you do have to look at each case in isolation. I was merely putting some additional information on this forum for consideration, especially in response to some comments that replacing a boiler that works but is inefficient will never make sense.

From a personal point of view, I have recently replaced my hot water cylinder with a more modern and better insulated version and am heating it with an immersion using excess solar or off-peak electricity. This is averaging 4.5kWh per day compared to the 7.5kWh of gas that was previously being consumed.

QrizB

Magnitio said:

I have recently replaced my hot water cylinder with a more modern and better insulated version and am heating it with an immersion using excess solar or off-peak electricity. This is averaging 4.5kWh per day compared to the 7.5kWh of gas that was previously being consumed.

Does your new tank still have a gas coil? Are you heating the same volume of water as before? With many water tanks, the gas heated volume is larger than the electrically heated one.

4.5kWh of electricity will heat about 75 litres of water from 10C to 60C, which is a lot less than the volume of most domestic hot water tanks.

Magnitio

QrizB said:

Magnitio said:

I have recently replaced my hot water cylinder with a more modern and better insulated version and am heating it with an immersion using excess solar or off-peak electricity. This is averaging 4.5kWh per day compared to the 7.5kWh of gas that was previously being consumed.

Does your new tank still have a gas coil? Are you heating the same volume of water as before? With many water tanks, the gas heated volume is larger than the electrically heated one.

4.5kWh of electricity will heat about 75 litres of water from 10C to 60C, which is a lot less than the volume of most domestic hot water tanks.

It does still have a heat exchanger coil. Same capacity as before - 117 litres. 27 inch immersion, so it doesn't quite heat as much of the tank as the coil, but it is sufficient for the volume of water that we use. It is rare that the tank is completely empty of hot water, so we don't usually have a situation where we are heating all of the water from 10C to 60C. The coil has been retained to provide the option of using the boiler during Winter.

The old tank was 34 years old (from what I can ascertain) and had a lot of scale on the coil making it inefficient. The pipes from the boiler to the tank are also quite long, so further adding to the heat loss.

BUFF

Zandoni said:

BUFF said:

Zandoni said:

BUFF said:

It was well known as bus control before Opentherm came along as an independent rather than proprietary variant. The original Opentherm specification was sold to the association by Honeywell.
Vaillant have proprietary e-Bus, Viessmann have K-Bus, Bosch Group have EMS & there are even manufacturers that have taken advantage of flexibility in Opentherm specification to make it more difficult for Opentherm devices from 3rd-party suppliers to run with their Opentherm boilers.

The heating industry generally seems to  to line up behind the reasons why a boiler running lower for longer is better for boiler & system life but you are allowed to have your own opinion.
 
Yes, I did say that "a new boiler+new controls all properly set up & used might" (not will).
Also note. not "new boiler" but "new boiler+new controls". I also said "it depends where you are coming from to start".
My last  "new boiler+new controls" change demonstrably has paid for itself over it's 13 years (14 heating seasons) which I attribute roughly 50% to generational (non-condensing balanced flue> condensing fan-flued) boiler efficiency savings  & 50% to efficiencies gained from using improved controls. However, and for the 3rd time now, I am also saying that I don't expect the next boiler+controls change to achieve that - the easy gains have been made & there is very limited room for improvement over what I currently have.

I'll leave you with your opinion but mine hasn't changed, I still think you should only change your boiler when it dies.

& I sttill don't get why you don't think that is the plan?
That is what I did last time (when the boiler required an uneonomic repair) & I have already said " I am planning on upgrading the controls when I next have to replace my boiler. "
For clarification, imo "dies" also includes the need for an uneconomic repair.

No I thought your plan is fine if the boiler is on its way out, I was really saying that I don’t think it’s economical to replace a good working boiler to save gas.

In general, I would agree with you (particularly as the no. of old, inefficient boilers in use continues to fall as time goes on) but if somebody does their sums for their system/usage & the figure suggest a reasonable ROI period then I don't have a problem (or a vote, it's their own choice/money).

seatbeltnoob said:

dont go combi, you'll regret it. stick to a system boiler.

you'll have to run the tap for 30 seconds to get hot water, and in cold winter mornings, it's agonising. if you are in the shower and someone runs the hot water taps anywhere in the house you'll get cut out of hot water.

combi boilers have issues every few years, 2 years ago divertor valve went, this year pcb went.

I have a combi with a small internal dhw storage tank (Worcester Highflow). I only heat the tank when about to use bath/shower but when in use it eliminates the wait for hot water (also increases dhw flow rates @) specific ΔT) & the pipe runs are shorter than when there was a storage cylinder. Original changeover to a combi was planned with a new kitchen to minimise additional disruption & work.
I know that it isn't an appropriate solution for a lot of people/houses but it suits my situation admirably.

Maybe lucky but this combi has run faultlessly for 13 years (I have no doubt just jinxed myself ).

seatbeltnoob

Magnitio said:

Hot water cylinders will typically lose between 1 and 2 kWh of heat every day, even those that are very well insulated. At 7p per kWh, that's £25 to £50 per annum. There are also inefficiencies in heating that water from the boiler. Replacing an old 75% efficient boiler with a 90+% efficient boiler could easily save a further £200 a year for heating a typical house. With the increasing gas prices, the savings will be even greater. There is also a significant environmental benefit of using less gas, as well as political if we can reduce our imports.

£25-£50 a year is well worth the price for good reliable hot water IMHO.

I'd gladly pay that premium and is a very small increase in comparison to the total bill.

Plus you save water and dont have to run the hot taps for 30 seconds to get flowing hot water.

I have a combi and it's miserable - every day we curse this combi.

Zandoni

seatbeltnoob said:

dont go combi, you'll regret it. stick to a system boiler.

you'll have to run the tap for 30 seconds to get hot water, and in cold winter mornings, it's agonising. if you are in the shower and someone runs the hot water taps anywhere in the house you'll get cut out of hot water.

combi boilers have issues every few years, 2 years ago divertor valve went, this year pcb went.

good thing with combis though is that central heating comes on fast. within 5 minutes the radiators all over the house are piping hot.

The time taken for hot water to get through can be lessened by changing the pipe work a bit, most engineers when fitting a boiler just connect up a few pipes and leave the water going all around the house before it gets to the taps.

BUFF

seatbeltnoob said:

Magnitio said:

Hot water cylinders will typically lose between 1 and 2 kWh of heat every day, even those that are very well insulated. At 7p per kWh, that's £25 to £50 per annum. There are also inefficiencies in heating that water from the boiler. Replacing an old 75% efficient boiler with a 90+% efficient boiler could easily save a further £200 a year for heating a typical house. With the increasing gas prices, the savings will be even greater. There is also a significant environmental benefit of using less gas, as well as political if we can reduce our imports.

£25-£50 a year is well worth the price for good reliable hot water IMHO.

I'd gladly pay that premium and is a very small increase in comparison to the total bill.

Plus you save water and dont have to run the hot taps for 30 seconds to get flowing hot water.

I have a combi and it's miserable - every day we curse this combi.

you have the wrong combi or, as Zandoni says, sub-optimal piping for your combi.

seatbeltnoob

the piping is as short as it can realistically be.

I think you lot might just be used to waiting for the hot water and underestimating how long you actually have to wait? Put your hot water tap and and time is with a stopwatch.

When I turn my taps on it takes about 5 seconds for the boiler to wake up - I can hear it firing up but it goes through several different stages before it's producing hot water at a hot temperature. It makes a humming noise as water runs through the boiler, then the flame comes on, then it starts producing hot water but it takes a while for the water to get hot and get to a suitable temperature.

All in all, from the moment I turn the tap on to getting hot water it's 45s-60s. Fine for summer. But during Winter time I have to wait for the water to warm up - The water comes in from a supply in the roof of the building block I think - becasse it's ice cold in winter.