It is all in the details. Documentation is quite extensive (but seldom read). Suspicions better are proven. Is it also used with a non Vaillant thermostat ?
Documentation on Vaillant is difficult to find. This is true for other aspects of home heating too. Websites abound with stories of misbehaving boilers and thermostats where the participants have tried and failed to get info from manufacturers and have instead had to resort to reverse engineering and guesswork. Generally the 'cleverer' the item the more baffling is its behaviour.
Manufacturers usually hide technical information for one of two reasons:
- they don't want their competitors to find out about their clever ideas
- they don't want their customers to find out about their stupid ideas
Manufacturers usually hide technical information for one of two reasons:
- they don't want their competitors to find out about their clever ideas
- they don't want their customers to find out about their stupid ideas
Here the Ecotec boilers are delivered with quite thick books for end users, installers and the infamous "schornsteinfeger". In these books also connection of other Vaillant periferals is discussed in detail. I wonder why they are scarce with info in the UK. I guess they gave up when they saw out of spec use too often 
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The Vaillant installation manual gives instructions on how to set various parameters via the 'installer' menu, but gives very little guidance on what the parameters mean and what value you might want them to be for a particular installation. I assume they provide this information via installer training sessions, but the customer is left in the dark and has to trust that the installer knows what he is doing.
Instructions are like
"To set the spurge algorithm select 'spurge' from the widget menu. To set the spurge algorithm to bodgit, select option 1. To set the spurge algorithm to budgit, select option 2. To set the spurge algorithm to bidgot, select option 3. Warning: do not select option 3 if the optional bidgot sensor is not fitted, as this may damage the device."
Instructions are like
"To set the spurge algorithm select 'spurge' from the widget menu. To set the spurge algorithm to bodgit, select option 1. To set the spurge algorithm to budgit, select option 2. To set the spurge algorithm to bidgot, select option 3. Warning: do not select option 3 if the optional bidgot sensor is not fitted, as this may damage the device."
I expect mine to be higher due to the timed overrun as mentioned earlier- my heating is coming on for shorter periods more frequently since fitting the TPI thermostat
> a new condensing boiler (claimed efficiency 90%)
US market gas hot-air furnaces typically tout 94.5% efficiency.
I believe it. My old "80%" burner, the smoke pipe would burn flesh. This new one, the smoke pipe runs "hardly warm". just a few degrees warmer than the air to the house. The smoke (dead clear but wet) runs in PVC pipe, so obviously they think it can NEVER get hot.
But efficiency definitions can be BS. I am still not sure if my "95%" includes the blower-power. The house-blower's waste heat is of course 99.9% efficient electric heat since it is in the house airbox. The smoke blower puts its heat in the combustion air, so gives a smaller boost to fire output. Yet the ratings seem to go only by gas BTU.
US market gas hot-air furnaces typically tout 94.5% efficiency.
I believe it. My old "80%" burner, the smoke pipe would burn flesh. This new one, the smoke pipe runs "hardly warm". just a few degrees warmer than the air to the house. The smoke (dead clear but wet) runs in PVC pipe, so obviously they think it can NEVER get hot.
But efficiency definitions can be BS. I am still not sure if my "95%" includes the blower-power. The house-blower's waste heat is of course 99.9% efficient electric heat since it is in the house airbox. The smoke blower puts its heat in the combustion air, so gives a smaller boost to fire output. Yet the ratings seem to go only by gas BTU.
I think they are usually AFUE "average fuel utilization efficiency".
Mine is claimed 96% It works pretty well.
I used about 40% less gas than the 'average house like mine in the neighborhood' - supposedly they pick 100 houses that are about the same size and age.
My 92% tankless water heater saves me about $4 a month over the small tank I had previously. It saves a lot of space, though, and it is nice to never run out of hot water.
> My 92% tankless water heater
My much-much older (75%?) tankless was nice when I needed hot water for 30 hours to clear a frozen sewer.
But (perhaps age and scum) it was dangerous for normal use. Not quick to start. Then it would scald. If you turned-down, or mixed cold, it might shut-off again. (Low water pressure is part of this; I did re-plumb to reduce feed line loss.) I pumped vinegar through the waterside, and cleaned the fireside.
I installed an *electric* water tank heater. Standard $279 job. In a cold basement (but extra wrap). The difference in our electric bill is not large. The improvement in comfort is worth it.
I do keep the gas tankless lit just-in-case. A few valves and it is on-line.
I have considered running them series. Heat with gas, hold with electric. So far it has not been worth the thinking.
FWIW: the tankless didn't save a heap of space the way it had been installed. It is much lower height, but with pipes and old-style smoke-pipe it left a fair amount of useless space.
My much-much older (75%?) tankless was nice when I needed hot water for 30 hours to clear a frozen sewer.
But (perhaps age and scum) it was dangerous for normal use. Not quick to start. Then it would scald. If you turned-down, or mixed cold, it might shut-off again. (Low water pressure is part of this; I did re-plumb to reduce feed line loss.) I pumped vinegar through the waterside, and cleaned the fireside.
I installed an *electric* water tank heater. Standard $279 job. In a cold basement (but extra wrap). The difference in our electric bill is not large. The improvement in comfort is worth it.
I do keep the gas tankless lit just-in-case. A few valves and it is on-line.
I have considered running them series. Heat with gas, hold with electric. So far it has not been worth the thinking.
FWIW: the tankless didn't save a heap of space the way it had been installed. It is much lower height, but with pipes and old-style smoke-pipe it left a fair amount of useless space.
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My tankless is a ~28"Hx18"Wx10"D box mounted to the wall under some ductwork and the 3" supply and return pipes (~160,000 BTU) go out the side wall in a joist bay. I set the temp to 114F and I have never been scalded. The modulating burner works very well and the minimum flow rate to start is something like 0.5 GPM, but it will go down to 0.2GPM before shutting off. Only real complaint is the fan drones a bit, but it is quieter than the water in the bath... It also takes a bit longer to get hot water, partly due to a longer pipe run and partly because the burner ramps up slowly.
https://www.menards.com/main/plumbi...664489551-c-8690.htm?tid=-5454742246243316842
BTW, GPM ratings on tankless water heaters are typically for a 35F rise. This means that here in MN at least, they will heat the water to 70-75F at rated flow rate in the winter.
Say you want a 110F bath and you have 40F water supply, you need a 70F increase, so your tankless is only good to half the rated flow. That is 4.2GPM in my case. A reasonably restricted shower will run about 2GPM and a bath faucet 1GPM, but a washing machine might run 3 or 4. My water heater works for me, but it might not work for 2 bathrooms and a clothes washer at once, depending on the season...
Formula - BTU/hr = 500*GPM*deltaT
There is certainly a similar formula in SI units for those in other parts of the world
Say you want a 110F bath and you have 40F water supply, you need a 70F increase, so your tankless is only good to half the rated flow. That is 4.2GPM in my case. A reasonably restricted shower will run about 2GPM and a bath faucet 1GPM, but a washing machine might run 3 or 4. My water heater works for me, but it might not work for 2 bathrooms and a clothes washer at once, depending on the season...
Formula - BTU/hr = 500*GPM*deltaT
There is certainly a similar formula in SI units for those in other parts of the world
Diesels don't have "throttles" in the sense of a valve that closes the input tract. A throttle is a petrol or gas (gas as in propane or methane) engine control.
Diesels simply reduce or increase the quantity of fuel to change the power.
It's the lack of a throttle that makes the diesl's low power output range so very much more efficient compared to the throtteled petrol engine. the diesel is not pumping against the nearly closed valve.
I am not aware of petrol engines that don't have a throttle, but I suppose clever electronics could control the petrol engine output with just a demand lever asking for more, or less power.
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You have spotted the error.
The boiler can never be more than 100% efficient.
The higher efficiency is calculated assuming that all of the latent heat contained in the steam is not recovered and all else adds up to 100%.
Then if any of the latent heat in the steam is recovered they claim >100% efficiency. Completely misleading and deliberately targeting the uninformed customer.
I think this method of calculation was made illegal in the UK.
Going back to the condensing boiler.
The boiler can condense ONLY if the flue gases are at a low enough temperature to allow some of the steam to condense.
That low flue gas temperature can only be achieved if the returning water temperature is low enough to allow the heat exchanger to cool the flue gas. i.e. the returning water temperature must be significantly lower than the the condensation temperature of the flue gas.
And here is the part that the heating system retailer don't divulge to the customer.
For a condensing boiler to achieve any condensing during the main "winter" heating period the room radiators need to be about twice the size of the radiators of a non condensing boiler.
Typically a non condensing boiler requires the difference between flow temperature and return temperature to be around 11Cdegrees. This is usually done where radiator flow temp is ~80 to 85degrees C and the return temperature is ~70 to 74degrees C
For a condensing system, the return temp must be much lower and most will be set to around 60degrees C, to achieve some condensing, but lower would release more of the latent heat in the steam.
A condensing boiler requires the radiators to have a higher differential temperature to extract sufficient heat to warm the room and to do that from a lower flow temperature. It's this dual requirement essential to condensing, that requires the extremely large radiators.
Most houses and householders will not permit such large radiators. We have lived with conventional designs for so long, we won't accept anything else.
Underfloor heating runs on far lower temperatures. In part because the rules requires the surface temperature of the exposed floor to be <29degrees C.
This lower operating temperature perfectly suits condenser boiler technology.
But the underfloor heating suppliers tell lies as well.
Does anyone have any interest in hearing that story?
The boiler can condense ONLY if the flue gases are at a low enough temperature to allow some of the steam to condense.
That low flue gas temperature can only be achieved if the returning water temperature is low enough to allow the heat exchanger to cool the flue gas. i.e. the returning water temperature must be significantly lower than the the condensation temperature of the flue gas.
And here is the part that the heating system retailer don't divulge to the customer.
For a condensing boiler to achieve any condensing during the main "winter" heating period the room radiators need to be about twice the size of the radiators of a non condensing boiler.
Typically a non condensing boiler requires the difference between flow temperature and return temperature to be around 11Cdegrees. This is usually done where radiator flow temp is ~80 to 85degrees C and the return temperature is ~70 to 74degrees C
For a condensing system, the return temp must be much lower and most will be set to around 60degrees C, to achieve some condensing, but lower would release more of the latent heat in the steam.
A condensing boiler requires the radiators to have a higher differential temperature to extract sufficient heat to warm the room and to do that from a lower flow temperature. It's this dual requirement essential to condensing, that requires the extremely large radiators.
Most houses and householders will not permit such large radiators. We have lived with conventional designs for so long, we won't accept anything else.
Underfloor heating runs on far lower temperatures. In part because the rules requires the surface temperature of the exposed floor to be <29degrees C.
This lower operating temperature perfectly suits condenser boiler technology.
But the underfloor heating suppliers tell lies as well.
Does anyone have any interest in hearing that story?
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I was working with a Vaillant system when down at my sister's during the week.
It was terrible, for confusing translations from german and for providing little information.
It took me over an hour to discover how to refill/recharge the radiator system to full pressure. No info anywhere. Except "consult the installer".
There were no wiring diagrams. Fortunately the replacement of the clever thermostat was easy.
But it had a 20page leaflet on designing/installing the flue. I suspect that was forced onto the supplier by UK law to prevent avoidable death.
It was an old combi. Very inefficient. Sister already has it earmarked for replacement and I have forewarned her on the big radiators "problem".
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As this thread is already somewhat off topic, I hope no-one will mind me posting this about Nuclear Fusion. I've no idea about the author's creds, but I can believe.
The Selling of ITER | New Energy Times - LENR News and Scientific References
The Selling of ITER | New Energy Times - LENR News and Scientific References
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