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Post by Telemachus on Jun 2, 2024 15:52:49 GMT
As to the heat anticipator, obviously I do understand how it works and what it is for. It is not rocket science. It makes the thermostat cycle more frequently in order to maintain a steadier room temperature, otherwise you would likely have a couple of degrees of oscillation. But it does this at the expense of cycling the heating system on and off. If there are no zone valves this may not matter too much but as I explained, in the case of my Mother’s system there are 3 zone valves. It does seem a fairly crap way of doing it but it seems to be standard practice in many systems. Or was, before load and weather compensation came in. Picking uo your one point, you obviously do not understand the action of the heat anticipator in a mechanical room stat. It simply makes a positive switch whereas without it, the contacts are likely to oscilate for a short period, especially with mains voltage which can arc a small gap. Most, virtually all popular ones from the last 7-8 years are rated A for efficiency. A modulating burner reduces the gas input in line with increasing return temperatures which is an accepted form of compensation, until the controls decide the room target temperature has been met when they switch off the boiler. In this condition your Vaillant all singing all dancing controler will do the same, except it apparently turns down the boiler thermostat to reduce flow temperatures. All boilers including yuors will have a boiler thermostat to set the flow temperature. Most of these are set within a digital panel programme but Ideal still do a knob which shows the temp in the panel. It is this temperature that we are advised to reduce to save energy, but obviously this will be noticeable to the occupants in cooler radiators. cooler radiators take longer to heat up a space although they will evetually get there depending on the insulation properties of the premises. There are products eg Nest, that will give you the oppotunity to remotely control your boiler and it is accepted that they do not 'talk the boiler's language' that they are about 1% less efficient than a boiler like your Vaillant. Industry tests put your boiler at abot 93-94%. An equivalent Worcester or Ideal shows up as about 92-93%. The link below makes interesting reading about the myths and let's say mistruths surrounding SEDBUK and Erp data. It also says that the most efficient flow temperature is 60-65oC with a return of 50oC. I would be wary of any return below 40oC as you may start getting condensation around the return port. Whilst it is not as destructive as it used to be on stee or cast heatexchangers, it can cause problems with sensors and control wiring. iheat.co.uk/boiler-help/energy-efficient-boilersRegarding the function of a heat anticipator, no sorry you are incorrect. It is not to make a “positive” switching action to avoid arcing, that function is built into the design of the bimetallic sensor (or whatever type of sensor it has) and contact action by means of positive mechanical feedback - when you rotate the dial of a mechanical thermostat you can hear the contacts clicking, that it the bimetallic sensor operated switch demonstrating its bitstable action with hysteresis. There is no setting of the thermostat where the contacts are just barely brushing each other. The switch is either on or off (with some milliseconds of contact bounce as is the case with any mechanical switch). The heat anticipator is a small heating element that, when on, heats the bimetallic strip/sensor to slightly above room temperature. This causes the thermostat to trip off at a slightly lower room temperature than it otherwise would. The room temperature will overshoot a bit due to the rads still being hot, and then things start to cool down. With the heat anticipator now unpowered, the sensor detects only room temperature and so it trips back on after only a slight drop in temperature, if any. The consequence is that instead of long slow cycles of heat and no heat and perhaps 2 or 3 degrees room temperature variation, you get more frequent cycles and more like 1 degree variation or even less. If you don’t believe me, please feel free to do your own research on the internet. You will find multiple websites describing the purpose and function of a heat anticipator, all of which agree with my line of thinking. Back to load compensation, you seem to think that any modulating boiler has load compensation. This is incorrect as I previously explained - load compensation is about automatically altering the flow temperature according to circumstances. You mention the inadvisability of return temperature below 40c but it is odd that modern boilers quote best efficiency with 50/30 operation, ie a return temperature of 30. Perhaps you are better informed than the manufacturers of virtually every modern boiler, but I somehow doubt it. The article mentions 60-65 flow temperature as being the most efficient. A brief examination of the spec of any modern condensing boiler will show this to be rubbish, the efficiency figures quoted at 50/30 are alway better that at 80/60 simply because the cooler the flow, the more efficient it is. But of course one could not install a boiler and set the max flow temperature to 50, chances are it would not adequately heat the room on a cold day and/or would take a long time to get the room up to temperature. So I think what he is saying is that around 60-65 is as low as you want to go with a fixed flow temperature. 60-65 is clearly more efficient than 80. But all this is irrelevant when you have load and weather compensation because the flow temperature becomes variable, it will be hot when it needs to be, and cooler when it can be in order to maximise efficiency.
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Post by brummieboy on Jun 2, 2024 16:57:24 GMT
We obviously have different opinions, mine is based on experience and trusted internet sites.
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Post by Telemachus on Jun 2, 2024 17:34:38 GMT
We obviously have different opinions, mine is based on experience and trusted internet sites. Yes. Mine is based on theory, recent practice, common sense and the majority of internet sites. But I am always open to learning new things so please could you share your trusted internet site that describes to your satisfaction the purpose and function of a heat anticipator in a domestic central heating thermostat?
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Post by deleted on Jun 2, 2024 18:02:24 GMT
And now you know how to fit a thermostat.
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Post by Telemachus on Jun 2, 2024 19:07:24 GMT
And now you know how to fit a thermostat. Yes but that bit was boring. Anyway, the whole heat anticipator thing is relevant to boating. Well, slightly. Well, it’s relevant to fridges as the same principle is applied to fridge thermostats. And people who replace built in thermostats with some modification to eg add an electronic thermostat to turn an inverter on and off (mains powered fridge) find the temperature control is not great. A built in fridge thermostat mostly measures fridge cabinet temperature but also is located close enough to the evaporator so that the coolant temperature also has an influence on what the thermostat measures. It is exactly the same idea as a heat anticipator only in reverse (a cold anticipator). Without this merging of cabinet and coolant temperatures the fridge temperature oscillates too much. Well I think it is interesting anyway. I fully appreciate that on here, it is probably way over most people’s heads.
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Post by Clinton Cool on Jun 2, 2024 19:31:30 GMT
It's certainly over my head but I now know how to wire my thermostat, that's good enough for me.
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Post by Telemachus on Jun 2, 2024 19:38:26 GMT
It's certainly over my head but I now know how to wire my thermostat, that's good enough for me. I strongly advise against wiring your thermostat over your head. You will get sore arms very quickly.
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Post by Clinton Cool on Jun 2, 2024 19:41:36 GMT
It's certainly over my head but I now know how to wire my thermostat, that's good enough for me. I strongly advise against wiring your thermostat over your head. You will get sore arms very quickly. Funnily enough, in order to connect the wires to the boiler, I'll have to twist my head to an awkward angle, likely holding a torch between my teeth. Over my head, yes, more or less.
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Post by brummieboy on Jun 2, 2024 21:48:15 GMT
We obviously have different opinions, mine is based on experience and trusted internet sites. Yes. Mine is based on theory, recent practice, common sense and the majority of internet sites. But I am always open to learning new things so please could you share your trusted internet site that describes to your satisfaction the purpose and function of a heat anticipator in a domestic central heating thermostat? It is well explained on the drayton combi stat data sheet which can be googled. That particular one has load options. The RTS 1 that Ricco has only has the one connection as it is designed specifically for the type of boiler he has. A lot of the websites that appear are american/canadian and really refer to a different type of thermostat with various adjustments that are not quite the same. As I said earlier, I'm sure when designing the controls, Drayton, Honeywell and Satchwell Sunvic knew exactly what was needed and manufactured to that requirement. The only temperature variation that will make a boiler cycle is the ambient temperature in the room. The heat anticipator will close off the thermostat just before the set point and let the latent heat achieve the required level. Your hasty intervention without being in possesion of the full details of Ricco's equipment was irresponsible. I see you have now expounded your wisdom into refrigeration, but really all you need to say is that equipment should be replaced in accordance with manufacturer's instructions. Maybe you can share all the wisdom of the sites that you find so informative.
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Post by Telemachus on Jun 2, 2024 22:54:57 GMT
Yes. Mine is based on theory, recent practice, common sense and the majority of internet sites. But I am always open to learning new things so please could you share your trusted internet site that describes to your satisfaction the purpose and function of a heat anticipator in a domestic central heating thermostat? It is well explained on the drayton combi stat data sheet which can be googled. That particular one has load options. The RTS 1 that Ricco has only has the one connection as it is designed specifically for the type of boiler he has. A lot of the websites that appear are american/canadian and really refer to a different type of thermostat with various adjustments that are not quite the same. As I said earlier, I'm sure when designing the controls, Drayton, Honeywell and Satchwell Sunvic knew exactly what was needed and manufactured to that requirement. The only temperature variation that will make a boiler cycle is the ambient temperature in the room. The heat anticipator will close off the thermostat just before the set point and let the latent heat achieve the required level. Your hasty intervention without being in possesion of the full details of Ricco's equipment was irresponsible. I see you have now expounded your wisdom into refrigeration, but really all you need to say is that equipment should be replaced in accordance with manufacturer's instructions. Maybe you can share all the wisdom of the sites that you find so informative. You yourself said that without the heat anticipator, “the switching differential will be varied and wide”. This I would agree with, well the wide bit at least. But then you went off on some rant about it being to eliminate arcing in the contacts, which I will consider to be bollocks unless you can provide evidence to the contrary, which I’m sure you can’t. I am aware that some American thermostats have an adjustable heat anticipator (simply by varying the resistance and hence the heat output of the anticipator) but the underlying concept remains the same. A boiler controlled by a thermostat with a heat anticipator will make the boiler cycle more than one without a heat anticipator. Surely you can see that if the boiler fires and shuts off with say a 0.25C differential room temperature, it will do so more frequently that if controlled by a cruder thermostat with say 2 degrees hysteresis? Ricco didn’t give us much to go on at the outset, hence my response was couched in various ifs and buts. But nothing in my response was irresponsible, or if you think it was please tell me exactly what it was. I suspect you just didn’t like me interfering in what you feel is your area of expertise.
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Post by brummieboy on Jun 3, 2024 9:39:28 GMT
It is well explained on the drayton combi stat data sheet which can be googled. That particular one has load options. The RTS 1 that Ricco has only has the one connection as it is designed specifically for the type of boiler he has. A lot of the websites that appear are american/canadian and really refer to a different type of thermostat with various adjustments that are not quite the same. As I said earlier, I'm sure when designing the controls, Drayton, Honeywell and Satchwell Sunvic knew exactly what was needed and manufactured to that requirement. The only temperature variation that will make a boiler cycle is the ambient temperature in the room. The heat anticipator will close off the thermostat just before the set point and let the latent heat achieve the required level. Your hasty intervention without being in possesion of the full details of Ricco's equipment was irresponsible. I see you have now expounded your wisdom into refrigeration, but really all you need to say is that equipment should be replaced in accordance with manufacturer's instructions. Maybe you can share all the wisdom of the sites that you find so informative. A boiler controlled by a thermostat with a heat anticipator will make the boiler cycle more than one without a heat anticipator. Surely you can see that if the boiler fires and shuts off with say a 0.25C differential room temperature, it will do so more frequently that if controlled by a cruder thermostat with say 2 degrees hysteresis? Ricco didn’t give us much to go on at the outset, hence my response was couched in various ifs and buts. But nothing in my response was irresponsible, or if you think it was please tell me exactly what it was. I suspect you just didn’t like me interfering in what you feel is your area of expertise. If you look at any of the data sheets for room thermostats, Idon't think you will find one with a 0.25c differential. This is a cheap attempt to dig yourself out of your hole. Room thermostats, which you refer to as crude, will operate at about 2-3 degrees differential which in terms of comfort is considered to be a reasonable expectation by the energy advisors who have proliferated since the 'energy crisis' Out of interes, what is the hysteresis of your all singing all dancing computer controlled system. When the target temperature is reached surely it must turn off the boiler? I can't see too many ifs and buts in your first response to Ricco. It was a bit like me telling someone who wanted to know how to fly a helicopter telling them you just need to balance of the throttle and the cyclic pitch.
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Post by Telemachus on Jun 3, 2024 10:45:26 GMT
A boiler controlled by a thermostat with a heat anticipator will make the boiler cycle more than one without a heat anticipator. Surely you can see that if the boiler fires and shuts off with say a 0.25C differential room temperature, it will do so more frequently that if controlled by a cruder thermostat with say 2 degrees hysteresis? Ricco didn’t give us much to go on at the outset, hence my response was couched in various ifs and buts. But nothing in my response was irresponsible, or if you think it was please tell me exactly what it was. I suspect you just didn’t like me interfering in what you feel is your area of expertise. If you look at any of the data sheets for room thermostats, Idon't think you will find one with a 0.25c differential. This is a cheap attempt to dig yourself out of your hole. Room thermostats, which you refer to as crude, will operate at about 2-3 degrees differential which in terms of comfort is considered to be a reasonable expectation by the energy advisors who have proliferated since the 'energy crisis' Out of interes, what is the hysteresis of your all singing all dancing computer controlled system. When the target temperature is reached surely it must turn off the boiler? I can't see too many ifs and buts in your first response to Ricco. It was a bit like me telling someone who wanted to know how to fly a helicopter telling them you just need to balance of the throttle and the cyclic pitch. I really think you don’t understand the concept of a heat anticipator. The mechanical part of a mechanical thermostat will typically have a hysteresis of a couple of degrees. But when the heat anticipator is connected, this reduces to much less. That is the whole point. The thermostat isn’t measuring room temperature, it is measuring room temperature mixed with the heat from the anticipator. So let’s say you set 20 degrees on the stat. Without the anticipator it might click off at 21.75 degrees and click on at 19.75 degrees. In terms of comfort, that is a lot of variation. With the anticipator it will click off at a sensor temperature or 21.75 degrees whilst the actual room might be around 20 degrees. With the heat anticipator now off, the extra temperature of it dissipates and the measured temperature falls to ambient, when the room cools to 19.75 it clicks back on again. So the room only has to drop 1/4 a degree. I hope this is now clear for you. You still don’t seem to get how modern boilers work. As the set temperature is approached the flow temperature is reduced. Ideally the flow would then remain constant at a low burner rate (the boiler has a near 10:1 modulation ratio). If the minimum burner rate is still too high, the burner will switch off but this only happens if it is fairly warm outside (Victorian 4 bedroom granite house in Scotland with poor insulation). The temperature display on the thermostat has 0.1degree resolution and once things have settled down, it is rarely more than 0.1 degree out. The thermostat “learns” the house and CH system thermal dynamics so it knows eg how much thermal overshoot is to be expected. There is still slight overshoot, maybe 0.2 degrees but that is pretty good. As an aside, with weather compensation you can specify a time you want the house to reach a certain temperature in the morning, the system will fire the boiler at the appropriate time in advance, so that the house has reached the specified temperature at the specified time, regardless of outside temperature. The last time I flew a helicopter with a throttle was 1981. Modern helicopters don’t have throttles, just like modern CH systems don’t have a bimetallic strip type mechanical thermostat.
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Post by brummieboy on Jun 3, 2024 11:04:51 GMT
Rattled a cage eh? I did not ask about the resolution of your temperature display, but about the hysteris. I'm sure some helicopters still have throttles, but the original post was about a system that is not new. Your answer was akin to the Irishmans reply when asked for directions "well, if I were you I wouldn't start from here" By the way, did you find out about fridge thermostats from your own attempts at 'improvement'?
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Post by Telemachus on Jun 3, 2024 12:43:36 GMT
Rattled a cage eh? I did not ask about the resolution of your temperature display, but about the hysteris. I'm sure some helicopters still have throttles, but the original post was about a system that is not new. Your answer was akin to the Irishmans reply when asked for directions "well, if I were you I wouldn't start from here" By the way, did you find out about fridge thermostats from your own attempts at 'improvement'? Sorry if your cage was rattled. There is no hysteresis normally, I thought I explained that. In fact I did explain that. That is the whole point of load compensation. If load compensation reaches its limit (burner at minimum and still too much heat) the boiler will turn off although of course the pump will carry on circulating the still-warm water. The boiler will kick in again when the ambient temperature has dropped 0.1 degree or at the expiry of the short cycle prevention timer. So worst case is 0.1degree hysteresis, normally the temperature doesn’t fluctuate as much as 0.1 degree because the thermostat is not an on or off device. It is a control system operating some kind of PID control loop, where the coefficients of the P, I and D are dynamically adjusted by the “learning” process. I then went on to provide additional information. Sorry if that offends you, but as is often said on here it is not up to one person to dictate what another person posts. I don’t think any helicopter made since about 1960 has a throttle that you normally have to use. Some do have throttles that come in to play only when there is a failure of the engine governing system. Modern helicopters generally don’t have throttles at all, they have a typically quadruplexed FADEC with multiple sources of data and various fallback modes meaning there is no point in installing a manual throttle. They just have an “off-idle-fly” 3 position switch. No I found out about fridge thermostats by contemplating how they could work with so much apparent hysteresis when the control knob is rotated, whilst being able to maintain a very steady temperature and a relatively fast cycle time of 30 mins or so. I was prompted to think about it when people on CWDF were considering fitting an external thermostat to a mains fridge to use it to turn an inverter on and off. We have a 12v fridge so it was for interest only.
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Post by brummieboy on Jun 3, 2024 14:00:29 GMT
Not my cage, yours, but then you know that. So to precis, both systems will cut off when the space temperature is reached. A mechanical thermostat on an older system will do the same. on older systems, if the flow temperature gets high, the burner cuts out with the room stat but the pump still runs until the space temperature is reached. One expects some improvement in the passage of time as has been shown. I dont pretend to know anything about modern (or even not so modern) helicopters, I used it to show that throwaway remarks can be made.
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