How are boilers tested when measuring their efficiency.

[hard-work]

In case you do not know.

1. Reciprocating piston engines have pistons violently changing direction vastly reducing efficiency.
2. A four-stroke cylinder produces a power stroke only on every other rotation of the crankshaft, with three strokes being non-power pumping losses.
3. It has high friction losses.
4. It has high parasitical losses via auxiliaries consuming HP from the crankshaft.
5. 80% of the energy in the tank is wasted.
6. It is heavy, requiring energy to propel it along a road.
7. The weight means heavy suspension, meaning more energy to propel the car down a road.
8. It needs a large engine bay, meaning more energy to propel the car down a road.
9. A full tank of fuel is heavy, meaning more energy to propel the car down a road.
10. It is complex.
11. It pollutes the air.

It is a crock of a power unit. In 20 years time few will be about as EVs take over. They will be curios and young people will say, "they used those air poisoning motors in cities!"

 

[shambolic]

And how much MPG do you get in yer ****e car @bernardgreen?
Bet it’s not what manufacturers claim.
Give it a rest as you are complete boring c@nt on this subject.
Don’t bore us, get a dossier together and take it to the highest levels where they will also tell to to foxtrot alpha off.

 

[Dan Robinson]

Mental has obviously never driven a decent petrol car. Nor I would wager an electric car.


I agree though that in terms of efficiency , they're a crock of poop, new or old. However, in terms of energy density and refuel time.... the powers that be are not investing or legislating enough yet to take EV's to the next level. Hence we'll be stuck with the domestic ICE for a while longer.


Making me itch for another go in my Brother's race spec eType.

 

[hard-work]

Dannyboy, thank you for you solid contribution.

Look at this. It is here Dannyboy, it is here, the tipping point is here. Prices of batteries and EVs will drop like a stone with the charging infrastructure already here, and getting bigger. After watching you can then run off and do some disco dancing.

 

[ericmark]

"What is a Condensing boiler?

Good question, if it boils the water then the condensing would be done in the radiators, not the boiler, and if it does not boil the water then clearly it's not a boiler.

However the latent heat, or condensing of the moisture is not referring to the circulating water or steam, but the water produced as we burn the fuel, I have seen two designs for a wood burner that condenses the water out of the flue gas, but in the main only gas or oil condense the moisture out of the flue gas, and to do this with a circulating water system the return water needs to be cool enough.

The "Rocket" solid fuel heater does not use water or air to transmit the heat into the room, it heats up stones, so there are exceptions, but in the main the problem is getting the return water cool enough.

So when the water heater is controlled by the eBUS then the return water can be kept very cool, but where the water temperature is used, then the hotter the return water the lower the flame height, so the water is hottest just before the boiler switches off, although one could allow the pump to run for a time after the boiler has switched off, in theory that will not work, and reason hot water has returned is the thermostatic radiator valves have closed causing the by-pass valve to open so the water has no where to circulate other than within the water heater.

So using the eBUS less heat is lost every time the boiler turns off. But next question is who actually uses the eBUS to control the boiler, clearly it will be used when the boiler is tested, but building management systems are expensive, so even if theory shows eTRV which talks to a central thermostat which in turn uses OpenTherm to tell the boiler flame height required, in practice very few systems actually use it.

Same applies to radiator type, modern idea is never turn either the radiator or boiler off, we just alter the output. (Modulate) And to save energy we only heat the room when required, so the room can both heat up quick and cool down quick we want to keep the quantity of circulating water down to a minimum. Before modulating systems the reverse was true, we wanted the water in the radiator to act as a heat reservoir, smoothing out the mark/space action of the boiler, but today best option is to control the fan speed in fan assisted radiators which because they are fan assisted can heat the room far faster.

However again theory and practice are very different. The radiator will send out information as to room temperature and fan speed, but the unit to collect this and adjust boiler output is super expensive, plus to use a fan to circulate the air, there is noise from the fan, and if there are any poorly insulated parts in the room, then circulating the air will increase losses.

Any semi-skilled guy can follow a plan putting pipe A into hole A and wire A onto terminal A and install a system using something like EvoHome. The software does all the cleaver stuff. However EvoHome and the like is not cheap, so the skilled man can do nearly the same using far cheaper equipment, now that takes skill. But he can only do it if he knows what is wanted. I know IT guys would have signs on their desks. "We did exactly what was asked, but it was not what was wanted." That is also true with central heating.

So you want the kitchen to heat up ready for your return, followed by the living room, and at 10 pm the living room is allowed to cool and bedrooms heated etc etc. However you live 25 miles from work, so the geofencing is set to 20 miles, that takes 30 minutes so heating has been off all day and comes on as you travel home. However the eTRV has a minimum setting of 16°C and set to 20°C within 15 minutes it has hit 18°C, however in order no to over shoot the system now slows up, so it is another hour and a half before it hits 20°C. By 10 pm the room is warm, and the eTRV switches to 16°C but again so it will not over shoot it looses 2°C quickly but then slows down, and only on the coldest of nights will it ever cool to 16°C. Added to that, loads of insulation inside home to outside, but very little between rooms, so bedroom may be set to 18°C but in the main it still sits at 20°C.

So all this cleaver control is completely wasted as the house simply will not warm up or cool down that quickly. So central heating is 60% house design and 40% central heating design, and if your house is not designed to be able to use all the smart controls, then they are simply a waste of money.

 

[bernardgreen]

Give it a rest as you are complete boring c@nt on this subject.

Why don't you and your fellow professionals on this forum rise to the challenge and explain to the DIYers and potential customers for new boilers how manufactures do arrive at the values for efficiency they quote. That would end the matter. Better than being rude to those you ask you a question that you choose not to answer. Or maybe you cannot answer it as the manufacturers have not released to you the information about testing procedures.

And how much MPG do you get in yer ****e car

Slightly off topic and not supportive of your case as motor manufacturers do provide details of the way cars are driven to obtain the MPG figures in the sales brochures.

Best that I am aware of was 67 MPG ( it's a desiel ) measured on a 183 mile journey, early morning, clear motorway, driven for best economy. Raining so maybe more slighty MPG that if it had been dry. ( Click HERE )

As a slight aside one manufacturer's MPG test run gave very high MPG, the manufacturers were honest and pointed out that the return journey had produced a very low MPG.

So central heating is 60% house design and 40% central heating design, and if your house is not designed to be able to use all the smart controls, then they are simply a waste of money.

Very true,

 

[durhamplumber]

Didn't we discuss this a few weeks back? It's possible if the input heat is calculated on net gas CV (water produced not condensed) but the output heat is measured, and some (not all) condensation occurs. But the ratio of gross CV to net CV for methane is 1.11, so even if complete condensation is achieved, and there are no losses, the efficiency calculated that way cannot exceed 111%. For pure hydrogen, the figure is 1.18. For higher molecular weight hydrocarbons, which are also present in natural gas, the figure is lower.
I see the thread about Navien boilers has been closed, but on that there was something about efficiency 127% being claimed. I couln't see any links which might have justified it, but on the basis above it's impossible. Can anybody explain where the 127% comes from?

Few weeks???bgreen has been yarping on about efficiency defying the laws of physics for donkeys years on this site

 

[bernardgreen]

Few weeks???bgreen has been yarping on about efficiency defying the laws of physics for donkeys years on this site

Accuracy please ""yarping on about manufacturer's claims for efficiency defying the laws of physics""

 

[hard-work]

Why don't you and your fellow professionals

Making money from a line does not fall into Professional.

 

[ericmark]

I have had three houses where I paid the heating bills.
1) House one hot air central heating, worked well, however before double glazing and circulating air with a large fan past single glazed windows resulted in a lot of heat loss so expensive to run.
2) Fitted myself, used on Myson radiator (fan assisted) rest standard, open plan house, too much heat went up stairs, fitting extra radiator down stairs and TRV upstairs cured all problems and it then worked very well.
3) Was parents house, started with open fires, then closed fires to burn coke and when steel works closed (supply of cheap coke) first central heating fitted, hot water was thermo syphon added a wireless thermostat and motorised valve for hot water, father always complained upstairs too hot. Everything ripped out an new combi condensate boiler fitted. I was worse than the old system, room temperatures went both ways too hot and too cold, and when dad died I tried to fix it. I tried all sorts, starting with adjusting lock shield valves, fitting two thermostats one for day and one for night, eTRV heads, then the break through, I fitted a TRV on the hall radiator where the wall thermostat was fitted. There was a 90% improvement, I will not say perfect, but in the main living room we got temperature swings from 18 to 28°C I will admit main problem was sun on bay window, but after all the alterations main being the extra TRV in hall and eTRV heads in two rooms, the swing went 20 to 22°C.

With prospects of moving likely I will again need to sort central heating, even just on Myson circulating air the room in my own house was uniform, no warm or cold areas, my mothers old house, in living room I could record 4°C difference within the room with cold and hot spots. However mothers house costs less to heat, yet bigger house and detached where mine was a semi. She had a more modern boiler however it also broke down more than mine, so not sure modern is good?

However it has all raised one big question in my mind. Are fan assisted radiators good or bad? Do you want hot and cold spots in the room? By the window in my mothers room it gets hot when the sun shines, do you want to move that heat to rest of room? or will that mean rest of room is too hot, thermometer on windowsill shows silly figures, 32°C in winter, but the plastic of thermometer may be that temperature, but the air is not. And as I found with first house circulate the air and you are paying dearly to heat up cold spots which one will never use, only the cat ever sat on the windowsill.

If the house is well insulated then likely the fan assisted radiator is good, think modern ones have around 5 speeds and as the target temperature raises from actual temperature the fan speeds up, the reverse as it is satisfied, plus off if water becomes cold.

But not sure how the modulating boiler will work with fan assisted radiators? There is very little restriction in water flow, water was maintained at around 75°C in old house very little difference between flow and return, boiler would auto kick in to top up temperature as required. But modern boiler will not do that, if the water is returned hot it will modulate the flame height. Maybe water needs to circulate in series not parallel? That is how it is done in schools.

When the fan stops the water still flows, with TRV and non fan radiators if one room is cold and all other rooms are hot, the water only flows through the radiator in the cold room, maybe also the by-pass valve as well, but all the heat the boiler can give goes to that one room, with fan speed control water still flows through radiators with no fan running, so it would return hot water to boiler closing it down.

May be it needs a storage tank? With multi-fuel systems they all heat a central storage tank which in turn supplies water to radiators, as long as bottom of tank is cool the boiler would run. However then we run into more control problems. The more one looks the more complex it gets. I was upset at first to hear central heating technicians called heating and ventilating engineers, I felt you should have over a level 3 education to be called an engineer, i.e. HNC, HND, Degree. However the more one looks into the problems of control, the more one starts to realise they deserve the title engineer.

In general engineers save money by using just enough to do the job, any fool can spend loads of money and heat the house, all it needs is a thermostatic electric fan heater in every room controlled by it's own timer, it will maintain the room at a steady temperature as and when required, simple. But that would cost a fortune to run, so in steps the engineer who says I can do better than that and it will cost a lot less to run and not that much more to install. However all too often what happens is the guys fitting it simply say on my slide rule it shows room 10 x 12 needs X size radiator so that's what's going in. No thought, no one says your settee will block a radiator there, so for it to work in that position it will need to be fan assisted. So better more it to other wall, no that will require more pipe. Central heating has very little planning, it is thrown in and the occupier has to try and make a silk purse out of a sows ear.

 

[fixitflav]

But not sure how the modulating boiler will work with fan assisted radiators? There is very little restriction in water flow, water was maintained at around 75°C in old house very little difference between flow and return, boiler would auto kick in to top up temperature as required. But modern boiler will not do that, if the water is returned hot it will modulate the flame height. Maybe water needs to circulate in series not parallel? That is how it is done in schools.

The boiler doesn't know whether the rads are fan-assisted or not, or not rads but some other load eg HW cylinder. It modulates the gas flow to maintain flow temperature setpoint. The setpoint could be fixed, or it could be varied eg if you have outdoor temperature compensation.

 

[vulcancontinental]

After listening to a protege piano player do something very tricky and difficult an old time blues player was challenged on why he was famous and the protege could not break through. The old timer said he could do all that but was paid because he knew what to leave out and still move people not leave them admiring his cleverness.