|
how hot do you run you CH boiler
John Rumm was thinking very hard :
I was not that keen on the idea that some times it would otherwise deliver 70 degree water to the taps. Having a TMV on the cylinder output is a bit of a compromise, since it means you don't have the benefit of running the very hot water through all the pipe work like you would with multiple TMVs at every point of use. I just have one TMV, on a toilet wash basin. I put that in so kids could use the single tap I installed, to wash their hands un-supervised, with no risk of too hot water. |
how hot do you run you CH boiler
"dennis@home" wrote in message ... On 12/01/2019 09:10, tim... wrote: "Harry Bloomfield" wrote in message ... John Rumm pretended : It needs a little bit of experimentation to set the profile the first time - basically waiting for colder days and seeing if the system still heats the place comfortably and quickly enough. If it doesn't, then you just tweak it up to a steeper curve. It also helps if you have appropriate rad sizes for the rooms, and the system is balanced. Balanced? I have always assumed there was no need to balance a system, where TRV's are installed. if TRVs can be set to reliably keep a room at, say 20 degrees, then it doesn't but if they can't, then it does I'm about to find out if the first line is true, because it is clear than my new systems is not balanced. As it is currently set, the lounge is like a sauna, and the rest of the house still cool. I actually don't have a problem with the latter, it's the former that's the issue tim Where is the room stat? in the hall way That is the big problem with TRVs, you have to have the system run whenever any rad wants heat and its difficult to impossible with only one room stat. works OK in my current house which is, presumably, balanced properly tim |
how hot do you run you CH boiler
On 12/01/2019 08:38, Harry Bloomfield wrote:
John Rumm pretended : It needs a little bit of experimentation to set the profile the first time - basically waiting for colder days and seeing if the system still heats the place comfortably and quickly enough. If it doesn't, then you just tweak it up to a steeper curve. It also helps if you have appropriate rad sizes for the rooms, and the system is balanced. Balanced? I have always assumed there was no need to balance a system, where TRV's are installed. Many CH installers would probably argue that is the case... but it can make a system less nice to live with. Especially if you have rooms that don't get adequate flow until nearly all the other rads have throttled on their TRVs, or worse, never get to set temp because the main stat has turned the whole system off. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
"Dave Plowman (News)" wrote in message ... In article , tim... wrote: Anyhow, at my current house it is 55 and works perfectly well You must have rather oversized rads? Nope they are tiny they are on all day The house is well insulated Why do you think that wouldn't work? tim -- *Failure is not an option. It's bundled with your software. Dave Plowman London SW To e-mail, change noise into sound. |
how hot do you run you CH boiler
|
how hot do you run you CH boiler
On 12/01/2019 10:25, RJH wrote:
On 12/01/2019 07:30, John Rumm wrote: On 12/01/2019 00:55, RJH wrote: On 11/01/2019 21:30, John Rumm wrote: On 11/01/2019 18:52, tim... wrote: I had a new Combi fitted today (in the to-be-moved-to house). Fitters told me that I should run this at 74 degrees. snip Anyhow, at my current house it is 55 and works perfectly well what do you guys/galls do I have weather compensation on mine, and so it chooses its own temperature based on the outside temp. Basically that means its runs as cool as it thinks it can get away with and still be able to reach the target set point temperature in a reasonable amount of time. (the relationship is set by choosing a mapping curve that reflects the rate of heat loss of the building). I don't follow how that can work properly, as for most homes different rooms will have a different 'curve'. Or does tweaking the TRV compensate? It seems to work well enough in practice. Each room also has a TRV, and I have the place split into two zones; upstairs and downstairs, so that will account for some variation. It needs a little bit of experimentation to set the profile the first time - basically waiting for colder days and seeing if the system still heats the place comfortably and quickly enough. If it doesn't, then you just tweak it up to a steeper curve. It also helps if you have appropriate rad sizes for the rooms, and the system is balanced. The response curves look like: http://wiki.diyfaq.org.uk/index.php/...tingCurve1.png IIRC the system defaults to the 1.2 line. If you live in a super insulted place / particularly sheltered location then you would tweak down. In my case (exposed location - solid wall construction), I needed to go up. I found the 1.8 curve worked well. The system is also smart enough to automatically shift the response curve vertically based on the currently demanded internal target temperature[1]: http://wiki.diyfaq.org.uk/index.php/...tingCurve2.png So if you tweak the room temp up or down during the day (or have different times programmed with different set point temps), then it can vary the flow temperature to match the requirement. [1] Note that all the system temperatures sensors (internal downstairs, internal upstairs, DHW cylinder, and external) are digitized and processed as actual temperatures, not just as on/off "call for heat" style demands. Thanks for that, interesting. And I hadn't realised such systems had a collection of sensors. Probably no more sensors, than any other zoned system (i.e. one for each stat, plus the external one), but the fact that it can read actual temperatures from each does open up some more possibilities. OT but loosely relevant, I use my CH as 2 zones - upstairs and downstairs. I'm really not going to replumb to add a properly zones system, and I was wondering if it's possible to isolate the upstairs zone with a three way motorised valve - simply cutting out the upstairs 'circuit'. You could do, although a pair of two port valves is the more common way of doing it. It does depends a bit on how the pipework is done. Some systems are easy (say where pipework for each floor of rads is run under the respective floor), and some very difficult (say where all the pipework is under the upstairs floor, and then branches both up and down to feed rads). A single switch would be easier than faffing about with 4 TRVs each evening. Indeed - or even a timer / programmable stat for each floor. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
On 12/01/2019 00:59, RJH wrote:
On 11/01/2019 23:33, Max Demian wrote: On 11/01/2019 18:52, tim... wrote: I had a new Combi fitted today (in the to-be-moved-to house). Fitters told me that I should run this at 74 degrees. Which I thought far too high, as 1) it makes the radiators too hot to touch 2) basic thermodynamics suggest that a better temperature profile will result from having the radiators at the lower temperate for longer period than a higher temperature for a shorter period I tried to explain this but was met with "The recommended temperature is required for the condenser to have any effect" The instruction manual for my Ideal says that the 'e' setting is best for condensing, which is quite hot. I don't understand this as I would have thought that the cooler the returning water temperature the more condensing. My understanding of the 'e' mark on my Ideal boiler's central heating temperature control is that any setting above is non-condensing. Any setting below and the boiler's condensing. That was my 'understanding', but not what was stated in the admittedly dumbed down instructions, which talked about the startup procedure as "lighting the boiler", as if it has a pilot light rather than igniting the gas as required. -- Max Demian |
how hot do you run you CH boiler
In article ,
tim... wrote: "Dave Plowman (News)" wrote in message ... In article , tim... wrote: Anyhow, at my current house it is 55 and works perfectly well You must have rather oversized rads? Nope they are tiny The physical size depends on the demand in that area. they are on all day The house is well insulated Why do you think that wouldn't work? Anything can work. But there is an ideal figure for rad temp for best efficiency. -- *If you lived in your car, you'd be home by now * Dave Plowman London SW To e-mail, change noise into sound. |
how hot do you run you CH boiler
On 12/01/2019 10:19, RJH wrote:
On 11/01/2019 23:33, Max Demian wrote: On 11/01/2019 18:52, tim... wrote: I had a new Combi fitted today (in the to-be-moved-to house). Fitters told me that I should run this at 74 degrees. Which I thought far too high, as 1) it makes the radiators too hot to touch 2) basic thermodynamics suggest that a better temperature profile will result from having the radiators at the lower temperate for longer period than a higher temperature for a shorter period I tried to explain this but was met with "The recommended temperature is required for the condenser to have any effect" The instruction manual for my Ideal says that the 'e' setting is best for condensing, which is quite hot. I don't understand this as I would have thought that the cooler the returning water temperature the more condensing. Just found the manual for my Ideal Logic: "The Logic + Combi is a high efficiency combination boiler which is most efficient when operating in condensing mode. The boiler will operate in this mode if the CH temperature control (C) is set to the €˜e position (economy mode) or below. This control should be set to a maximum for very cold periods". I downloaded the manual and it omits the critical "or below". -- Max Demian |
how hot do you run you CH boiler
On 12/01/2019 13:46, Dave Plowman (News) wrote:
In article , tim... wrote: "Dave Plowman (News)" wrote in message ... In article , tim... wrote: Anyhow, at my current house it is 55 and works perfectly well You must have rather oversized rads? Nope they are tiny The physical size depends on the demand in that area. they are on all day The house is well insulated Why do you think that wouldn't work? Anything can work. But there is an ideal figure for rad temp for best efficiency. Best efficiency as far as the radiator is concerned is as hot as practical - the higher the deltaT between radiator and the room air then the more it radiates. If you have the heating on 24/7 then yes you can get away with low rad. temperatures, but for fastest response where the heating is timed then hotter is better. If you have intelligent thermostats like Hive or Nest then they will learn the thermal characteristics of the monitored room and minimise temperature overshoot by shutting down the boiler before the set temperature is reached. |
how hot do you run you CH boiler
"Dave Plowman (News)" wrote in message ... In article , tim... wrote: "Dave Plowman (News)" wrote in message ... In article , tim... wrote: Anyhow, at my current house it is 55 and works perfectly well You must have rather oversized rads? Nope they are tiny The physical size depends on the demand in that area. they are on all day The house is well insulated Why do you think that wouldn't work? Anything can work. But there is an ideal figure for rad temp for best efficiency. I'm not seeking efficiency I'm seeking all of the rooms at the same temp tim |
how hot do you run you CH boiler
On 12/01/2019 09:28, Harry Bloomfield wrote:
John Rumm formulated the question : IME many of the Vaillant boilers do support split temperature operation, but it does depends on what controls you have them paired with. The 400 series Vaillant I did (probably previous model range, since this was = 12 years ago), actually had separate knobs on the front for CH and DHW flow temperatures. Although that was retrofitted into system with traditional controls that could not distinguish between the source of the call for heat - hence the DHW control never came into play and it ran like your system does. The blurb on their web site: https://www.vaillant.co.uk/for-insta...ler-26116.html Seems to suggest its compatible with the VRC 700 weather compensating controls, so that ought to allow split temperature as well. I have studied it and not found any obvious way to split the temperature. I even spoke to Vailant and they confirmed there was no way it could be done. I suspect they are talking nonsense or at crossed purposes. It may be that it can't be done with the installation you have, however if you are prepared to add controls then it looks straight forward. If it (the compensator) is anything like mine (a VR470), then you can set the temperature for two "uncontrolled"[1] zones, and DHW separately in the programming. I also have a VR61 control module that lets you integrate traditional 240V zone valves etc into the controls. [1] They seem to call what most people would think of as a zone controlled with valves and a thermostat, an "uncontrolled" zone. They reserve the term controlled for ones with active blending valves for UFH where the controls can directly set the UFH zone flow temperature independently of the main boiler flow temp. Yup, have a look at: https://www.vaillant.co.uk/downloads...al-1000027.pdf See the user manual section 5.2.1.2: https://www.vaillant.co.uk/downloads...03-1000692.pdf That definitely allows independent control of CH and DHW temperatures. (the VR700 has way more toys that you will need - I just picked that one because it was listed on the 400 series page. I expect the older VR470 would be fine as well) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
On 12/01/2019 11:39, Harry Bloomfield wrote:
dennis@home brought next idea : IIRC one of the add on controllers allows for different temps when running HW and heating but I don't recall which. It would have to be something which interacted directly with the boiler and Vailant said there was nothing able to do that, when I spoke to them. The boiler has the built in interfaces for the fancier control systems, I understand, but little detail to be found about these extra systems. One of the problems I found with the Vaillant documentation, was that there is lots of low level detail stuff, but not so much "big picture" stuff to tell you what components you need to achieve which jobs. (perhaps that is what they train their registered installers with!) In the end it was just a case of reading through all the detail stuff until you can mentally put together what bits are going to do what you need. But basically you need a weather compensator, and probably an interface box to let it communicate with traditional valves etc. In my case I went for a VR470 and a VR61 (there is also another aux mini controller / stat to monitor the upstairs temp - but you can do without that). You use the VR470 as the interface to configure and control everything else. It acts as the central point for the timer / stat / weather compensator, and then a load of other facilities if you want them[1]. The interface box converts the demands of the controller delivered over eBus, to relays etc that can switch 240V to move 2/3 port valves. [1] From the handy "cylinder boost", and "holiday mode", to the more esoteric UFH screed drying programs, DHW anti legionella cycle, ctrolling aux pumps like secondary circulation pumps or solar collection pumps etc. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
John Rumm formulated on Saturday :
I suspect they are talking nonsense or at crossed purposes. It may be that it can't be done with the installation you have, however if you are prepared to add controls then it looks straight forward. All I have at the moment, is a Danfoss (I think) time clock, which sets when CH and HW are available. A three port valve. A wireless room stat and a wired HW cylinder stat. The original boiler had just a live (when called) neutral and earth. I added an extra pair in from boiler back to pump, to enable to boiler to decide when the pump needed to be run, when the new boiler was installed. |
how hot do you run you CH boiler
On 12/01/2019 10:25, RJH wrote:
OT but loosely relevant, I use my CH as 2 zones - upstairs and downstairs. I'm really not going to replumb to add a properly zones system, and I was wondering if it's possible to isolate the upstairs zone with a three way motorised valve - simply cutting out the upstairs 'circuit'. If the pipework is in the right place a two port valve will isolate the upstairs. A single switch would be easier than faffing about with 4 TRVs each evening. |
how hot do you run you CH boiler
"Andy Bennet" wrote in message ... On 12/01/2019 13:46, Dave Plowman (News) wrote: In article , tim... wrote: "Dave Plowman (News)" wrote in message ... In article , tim... wrote: Anyhow, at my current house it is 55 and works perfectly well You must have rather oversized rads? Nope they are tiny The physical size depends on the demand in that area. they are on all day The house is well insulated Why do you think that wouldn't work? Anything can work. But there is an ideal figure for rad temp for best efficiency. Best efficiency efficient in what way? as far as the radiator is concerned is as hot as practical - the higher the deltaT between radiator and the room air then the more it radiates. If you have the heating on 24/7 then yes you can get away with low rad. Which is what I do have temperatures, but for fastest response where the heating is timed then hotter is better. I have no need for faster response. I want constant moderate temperature tim |
how hot do you run you CH boiler
In article ,
tim... wrote: Anything can work. But there is an ideal figure for rad temp for best efficiency. I'm not seeking efficiency I'm seeking all of the rooms at the same temp I'm curious about that. You said with the boiler set to 74 degrees, the rad were too hot to touch? How can that be with the rooms at the correct temperture if they are OK at 55 degrees? -- *Nostalgia isn't what is used to be. Dave Plowman London SW To e-mail, change noise into sound. |
how hot do you run you CH boiler
On 12/01/2019 13:32, tim... wrote:
"John Rumm" wrote in message o.uk... On 12/01/2019 09:28, wrote: On 12/01/2019 08:56, tim... wrote: wrote in message ... On 11/01/2019 21:30, John Rumm wrote: On 11/01/2019 18:52, tim... wrote: I had a new Combi fitted today (in the to-be-moved-to house). Fitters told me that I should run this at 74 degrees. Which I thought far too high, as Indeed... 1) it makes the radiators too hot to touch 2) basic thermodynamics suggest that a better temperature profile will result from having the radiators at the lower temperate for longer period than a higher temperature for a shorter period It might be required in particularly cold weather, but most of the time you will be able to use less. I tried to explain this but was met with "The recommended temperature is required for the condenser to have any effect" You will most heat recovered from the condenser when the return temperature is below about 54 degrees (the dew point of the flue gasses). and the completely bogus "the temperature of the water in the radiators is set by the TRVs not the boiler temp.Â* I couldn't persuade the guy that he was taking bollox, he played the "I'm the experience heating engineer card and I know better than you" card. **** Anyhow, at my current house it is 55 and works perfectly well what do you guys/galls do I have weather compensation on mine, and so it chooses its own temperature based on the outside temp. Basically that means its runs as cool as it thinks it can get away with and still be able to reach the target set point temperature in a reasonable amount of time. (the relationship is set by choosing a mapping curve that reflects the rate of heat loss of the building). Currently the external temp is 6.5 deg C, and the flow temp is running at 54 deg. If it were to go well below 0, then it might push the flow temp up into the 70s. When its milder it might run flow temps down in the 40s. I thought the advice was to heat DHW to 60 degrees to avoid the risk of legionella, and that's not going to happen if the boiler's running at a lower temp. the temp for the hot water and CH system are set independently in a combi I was replying to John (but had forgotten about combis) The combi won't usually get it any hotter (since flow rate and temperature are mutually exclusive), but the again there is no significant store of water to act as a breeding ground either. the linked to article said that the water in a shower head was sufficient Not much way round that unless you like 70 degree showers ;-) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
On 12/01/2019 14:40, Harry Bloomfield wrote:
John Rumm formulated on Saturday : I suspect they are talking nonsense or at crossed purposes. It may be that it can't be done with the installation you have, however if you are prepared to add controls then it looks straight forward. All I have at the moment, is a Danfoss (I think) time clock, which sets when CH and HW are available. A three port valve. A wireless room stat and a wired HW cylinder stat. The original boiler had just a live (when called) neutral and earth. I added an extra pair in from boiler back to pump, to enable to boiler to decide when the pump needed to be run, when the new boiler was installed. So you would need a bit of rejigging to move to split temperature operation. The VR weather comp replaces the timer and stat. You probably want a pair of two port valves in place of the mid position valve - although with a bit of thought you may be able to achieve the logic required with what you have. Swap the cylinder stat for a NTC thermistor, and add a suitable wiring centre. You would need an extra cable from the cylinder to the boiler (that threw me, I was expecting the cylinder NTC to connect to the wiring centre!), and to install an external NTC somewhere. Doable enough, but whether its worth the hassle at this stage only you can decide. It might knock a few percent off the gas bill, and will make the place a bit more comfortable year round. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
On 12/01/2019 13:08, Dave Plowman (News) wrote:
In article , tim... wrote: Anyhow, at my current house it is 55 and works perfectly well You must have rather oversized rads? If they have been sized for the typical -3 outside temp, then they ought to have loads of spare capacity with the current weather. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
On 12/01/2019 10:25, RJH wrote:
On 12/01/2019 07:30, John Rumm wrote: On 12/01/2019 00:55, RJH wrote: On 11/01/2019 21:30, John Rumm wrote: On 11/01/2019 18:52, tim... wrote: I had a new Combi fitted today (in the to-be-moved-to house). Fitters told me that I should run this at 74 degrees. snip Anyhow, at my current house it is 55 and works perfectly well what do you guys/galls do I have weather compensation on mine, and so it chooses its own temperature based on the outside temp. Basically that means its runs as cool as it thinks it can get away with and still be able to reach the target set point temperature in a reasonable amount of time. (the relationship is set by choosing a mapping curve that reflects the rate of heat loss of the building). I don't follow how that can work properly, as for most homes different rooms will have a different 'curve'. Or does tweaking the TRV compensate? It seems to work well enough in practice. Each room also has a TRV, and I have the place split into two zones; upstairs and downstairs, so that will account for some variation. It needs a little bit of experimentation to set the profile the first time - basically waiting for colder days and seeing if the system still heats the place comfortably and quickly enough. If it doesn't, then you just tweak it up to a steeper curve. It also helps if you have appropriate rad sizes for the rooms, and the system is balanced. The response curves look like: http://wiki.diyfaq.org.uk/index.php/...tingCurve1.png IIRC the system defaults to the 1.2 line. If you live in a super insulted place / particularly sheltered location then you would tweak down. In my case (exposed location - solid wall construction), I needed to go up. I found the 1.8 curve worked well. The system is also smart enough to automatically shift the response curve vertically based on the currently demanded internal target temperature[1]: http://wiki.diyfaq.org.uk/index.php/...tingCurve2.png So if you tweak the room temp up or down during the day (or have different times programmed with different set point temps), then it can vary the flow temperature to match the requirement. [1] Note that all the system temperatures sensors (internal downstairs, internal upstairs, DHW cylinder, and external) are digitized and processed as actual temperatures, not just as on/off "call for heat" style demands. Thanks for that, interesting. And I hadn't realised such systems had a collection of sensors. OT but loosely relevant, I use my CH as 2 zones - upstairs and downstairs. I'm really not going to replumb to add a properly zones system, and I was wondering if it's possible to isolate the upstairs zone with a three way motorised valve - simply cutting out the upstairs 'circuit'. A single switch would be easier than faffing about with 4 TRVs each evening. Look at the Honeywell Evohome system http://www.heatingcontrols.honeywell.../evohome-Main/ |
how hot do you run you CH boiler
on 12/01/2019, John Rumm supposed :
So you would need a bit of rejigging to move to split temperature operation. The VR weather comp replaces the timer and stat. You probably want a pair of two port valves in place of the mid position valve - although with a bit of thought you may be able to achieve the logic required with what you have. Swap the cylinder stat for a NTC thermistor, and add a suitable wiring centre. You would need an extra cable from the cylinder to the boiler (that threw me, I was expecting the cylinder NTC to connect to the wiring centre!), and to install an external NTC somewhere. Doable enough, but whether its worth the hassle at this stage only you can decide. It might knock a few percent off the gas bill, and will make the place a bit more comfortable year round. It sounds like a lot of work, just to get around a limitation of the boiler design. I have though, my eye on a 470 complete with the outdoor sensor. So to check my understanding - The 470 is a complete time-clock and system monitor and room temperature sensor built into it? With the outdoor sensor, it becomes clever system able to adapt to set the boiler temperature as needed. It has the built in function to monitor an NTC on the HW cylinder and that temperature can be set separately. |
how hot do you run you CH boiler
"Dave Plowman (News)" wrote in message ... In article , tim... wrote: Anything can work. But there is an ideal figure for rad temp for best efficiency. I'm not seeking efficiency I'm seeking all of the rooms at the same temp I'm curious about that. You said with the boiler set to 74 degrees, the rad were too hot to touch? How can that be with the rooms at the correct temperture if they are OK at 55 degrees? two different boilers (two different houses) I have yet to try the new boiler at a lower temp tim |
how hot do you run you CH boiler
On 12/01/2019 19:15, Harry Bloomfield wrote:
on 12/01/2019, John Rumm supposed : So you would need a bit of rejigging to move to split temperature operation. The VR weather comp replaces the timer and stat. You probably want a pair of two port valves in place of the mid position valve - although with a bit of thought you may be able to achieve the logic required with what you have. Swap the cylinder stat for a NTC thermistor, and add a suitable wiring centre. You would need an extra cable from the cylinder to the boiler (that threw me, I was expecting the cylinder NTC to connect to the wiring centre!), and to install an external NTC somewhere. Doable enough, but whether its worth the hassle at this stage only you can decide. It might knock a few percent off the gas bill, and will make the place a bit more comfortable year round. It sounds like a lot of work, just to get around a limitation of the boiler design. Not sure you can really call it a limitation of the design - at least they provide the facility in the first place, unlike many. I have though, my eye on a 470 complete with the outdoor sensor. You would probably need the VR61 or similar as well to connect to the zone valves. So to check my understanding - The 470 is a complete time-clock and system monitor and room temperature sensor built into it? Yup... and an interface to pretty much anything else the system can do. With the outdoor sensor, it becomes clever system able to adapt to set the boiler temperature as needed. Yup. It has the built in function to monitor an NTC on the HW cylinder and that temperature can be set separately. ISTR the NTC cylinder sensor and the external sensor connect back to the boiler directly, but the overall effect is the same. You can have independent temperature settings for CH and DHW. Needless to say that precludes the system running Y plan with the valve in mid position, and so favours modern fast recovery cylinders. (if you program CH and DHW to be active at the same time, it squeezes reheats of the DHW in between periods where the CH is satisfied (perhaps with priority to the DHW) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
On Saturday, 12 January 2019 09:28:26 UTC, Harry Bloomfield wrote:
John Rumm formulated the question : IME many of the Vaillant boilers do support split temperature operation, but it does depends on what controls you have them paired with. The 400 series Vaillant I did (probably previous model range, since this was = 12 years ago), actually had separate knobs on the front for CH and DHW flow temperatures. Although that was retrofitted into system with traditional controls that could not distinguish between the source of the call for heat - hence the DHW control never came into play and it ran like your system does. The blurb on their web site: https://www.vaillant.co.uk/for-insta...ler-26116.html Seems to suggest its compatible with the VRC 700 weather compensating controls, so that ought to allow split temperature as well. I have studied it and not found any obvious way to split the temperature. I even spoke to Vailant and they confirmed there was no way it could be done. If the Vaillant has 2 separate call for heat signals for DHW & CH it would be simple enough to split the temp, at least if the boiler has 2 separate temp settings for the 2 circuits, and the Vaillant 400 series I'm familiar with does. Where is the problem happening? NT |
how hot do you run you CH boiler
On Saturday, 12 January 2019 13:31:13 UTC, John Rumm wrote:
On 12/01/2019 08:38, Harry Bloomfield wrote: John Rumm pretended : It needs a little bit of experimentation to set the profile the first time - basically waiting for colder days and seeing if the system still heats the place comfortably and quickly enough. If it doesn't, then you just tweak it up to a steeper curve. It also helps if you have appropriate rad sizes for the rooms, and the system is balanced. Balanced? I have always assumed there was no need to balance a system, where TRV's are installed. Many CH installers would probably argue that is the case... but it can make a system less nice to live with. Especially if you have rooms that don't get adequate flow until nearly all the other rads have throttled on their TRVs, or worse, never get to set temp because the main stat has turned the whole system off. IMLE it's essential to balance the system with TRVs set to max temp before using the TRVs to improve balancing as needs change. NT |
how hot do you run you CH boiler
on 12/01/2019, John Rumm supposed :
Not sure you can really call it a limitation of the design - at least they provide the facility in the first place, unlike many. ..All it would need to enable a split temperature, is 2x call inputs for heat instead of the single one it has at the moment. Plus the two temperature settings in the software, to replace the single temperature. A fairly simple fix at the design stage. Needless to say that precludes the system running Y plan with the valve in mid position, and so favours modern fast recovery cylinders. (if you program CH and DHW to be active at the same time, it squeezes reheats of the DHW in between periods where the CH is satisfied (perhaps with priority to the DHW) That would not usually be an issue here. The DHW is usually brought up to temperature in less than 20 minutes. 20 minutes with no CH input would not be noticed. |
how hot do you run you CH boiler
On 13/01/2019 10:01, Harry Bloomfield wrote:
on 12/01/2019, John Rumm supposed : Not sure you can really call it a limitation of the design - at least they provide the facility in the first place, unlike many. .All it would need to enable a split temperature, is 2x call inputs for heat instead of the single one it has at the moment. Plus the two temperature settings in the software, to replace the single temperature. A fairly simple fix at the design stage. Oddly the older version of the 400 series had the separate temperature knobs on the front, although I also have vague memories of there being reported problems using weather compensation on those. So perhaps they "fixed" it by going to the system used on the 600 series. Needless to say that precludes the system running Y plan with the valve in mid position, and so favours modern fast recovery cylinders. (if you program CH and DHW to be active at the same time, it squeezes reheats of the DHW in between periods where the CH is satisfied (perhaps with priority to the DHW) That would not usually be an issue here. The DHW is usually brought up to temperature in less than 20 minutes. 20 minutes with no CH input would not be noticed. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
|
how hot do you run you CH boiler
On 13/01/2019 03:09, wrote:
On Saturday, 12 January 2019 09:28:26 UTC, Harry Bloomfield wrote: John Rumm formulated the question : IME many of the Vaillant boilers do support split temperature operation, but it does depends on what controls you have them paired with. The 400 series Vaillant I did (probably previous model range, since this was = 12 years ago), actually had separate knobs on the front for CH and DHW flow temperatures. Although that was retrofitted into system with traditional controls that could not distinguish between the source of the call for heat - hence the DHW control never came into play and it ran like your system does. The blurb on their web site: https://www.vaillant.co.uk/for-insta...ler-26116.html Seems to suggest its compatible with the VRC 700 weather compensating controls, so that ought to allow split temperature as well. I have studied it and not found any obvious way to split the temperature. I even spoke to Vailant and they confirmed there was no way it could be done. If the Vaillant has 2 separate call for heat signals for DHW & CH it would be simple enough to split the temp, at least if the boiler has 2 separate temp settings for the 2 circuits, and the Vaillant 400 series I'm familiar with does. Where is the problem happening? The ecoFit Pure does not appear to have separate inputs: https://www.vaillant.co.uk/downloads...ual-876622.pdf However I just found this: https://www.vaillant.co.uk/downloads...ons-261442.pdf In its description it says: "The Control Center VR 65 offers a solution to allow Vaillant low voltage €˜eBUS controls to be used with the traditional 230 V zone valves and DHW storage cylinder in the English market. Information about the heat required by the cylinder is forwarded by the Control Center VR 65 to the Vaillant ecoTEC heating appliance. The boiler then decides whether a hot water request has to be fulfilled and sends a signal to position the 230 V zone valves via the VR 65. In this way, the boiler can store different target tempera- tures for heating and warm water operation. Standard 230 V components can be integrated into the Vaillant eBUS system via the Control Center VR 65." also: "The Control Center VR 65 is an eBUS system compo- nent. It is responsible for the communication between the DHW cylinder, the boiler and external 230 V 2- or 3-port valves. Note! The VR 65 is designed to control one 3-port valve or two 2-port valves. Systems requiring more zone valves or a combination of 3-port and 2-port valves are not possible." Installation: "The Control Center can be wall-mounted near to the DHW cylinder. The hot water and heating programs as well as all required parameters are set at the VRT 360 or VRC 400. All heating circuit connections are made at the Control Center using a ProE plug" of the VR360 it says: "VRT 360 Digital room temperature thermostat with daily/weekly program for time and temperature control of heating and hot water. Designed for wall mounting. There are three individually programmable time win- dows per day for heating, hot water and a hot water circulation pump. Different target room temperatures can be set for each time window. The thermostat can be set to run a weekly or a daily program. By activating the calendar function, an automatic summer/winter changeover is activated." Which sounds like you may be able to do: VRT360 + VR65, conventional 3 port valve, and conventional cylinder stat. No need to go fully weather comp. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
On 12/01/2019 22:19, John Rumm wrote:
I have though, my eye on a 470 complete with the outdoor sensor. You would probably need the VR61 or similar as well to connect to the zone valves. Better be quick.. The VR61 is obsolete and in clearance on most sites. I don't see an alternative on the valiant site. |
how hot do you run you CH boiler
John Rumm has brought this to us :
The ecoFit Pure does not appear to have separate inputs: https://www.vaillant.co.uk/downloads...ual-876622.pdf However I just found this: https://www.vaillant.co.uk/downloads...ons-261442.pdf In its description it says: Thanks, I am looking at that now.. |
how hot do you run you CH boiler
In article ,
John Rumm wrote: On 12/01/2019 13:08, Dave Plowman (News) wrote: In article , tim... wrote: Anyhow, at my current house it is 55 and works perfectly well You must have rather oversized rads? If they have been sized for the typical -3 outside temp, then they ought to have loads of spare capacity with the current weather. Of course. But would you want to fiddle with boiler temperture on a cold snap? Seems a rather old fashioned way of doing things. -- *Gravity is a myth, the earth sucks * Dave Plowman London SW To e-mail, change noise into sound. |
how hot do you run you CH boiler
In article ,
tim... wrote: I'm curious about that. You said with the boiler set to 74 degrees, the rad were too hot to touch? How can that be with the rooms at the correct temperture if they are OK at 55 degrees? two different boilers (two different houses) I have yet to try the new boiler at a lower temp Ah - right. With my Viessmann which has weather comp, the rads in the main room - no TRVs - would perhaps be too hot to touch when the system first comes on - but soon drop back to a lower temp. If you ran it 24/7, unless it was very cold, they've never be too hot to touch - although the rads I have include a faceplate which doesn't get up to the full water temp (Thermapanels - bought more for the look than this feature, many years ago) -- *All generalizations are false. Dave Plowman London SW To e-mail, change noise into sound. |
how hot do you run you CH boiler
On Sunday, 13 January 2019 10:34:57 UTC, Harry Bloomfield wrote:
tabbypurr wrote : If the Vaillant has 2 separate call for heat signals for DHW & CH it would be simple enough to split the temp, at least if the boiler has 2 separate temp settings for the 2 circuits, and the Vaillant 400 series I'm familiar with does. Where is the problem happening? It is a Vaillant 418 ECOfit Pure. It only has one input for call for heat, a permanent supply, plus an output for the pump. It also only has a single temperature setting, which I presently have set for max (75C). From cold, the boiler runs flat out until its output nears 75C, then it begins to modulate its heat output gradually down. We like the HW hot, so have it set at 75C for HW. The HW is set to come on for an hour per day, to bring the tank up to temperature, though when more HW is needed like when taking a bath, we press a 1 hour override button. 75C is unnecessary for the CH and not as economic as 60C would be, so I am looking for a workaround to allow for split HW v CH boiler temperatures. My first attempt at a split was a disaster... I added an adjustable thermostat to the CH pipe, just past the 3 port valve, wired to interrupt the CH call for heat wire when the pipe got to 60C. Which it did perfectly, but that caused the boiler to cycle frequently on and off, as the pipe temperature rapidly cooled and reheated. It also defeated the boiler's ramping down (modulating) its output. Another way I had thought of, was to fool the boilers own output temperature sensor, so when the call is for CH, it sees a false higher than actual temperature. I could probably manage that, with an extra call for CH wire back to the boiler (easy), a simple relay and a bit of jiggery pockery in the boiler sensor circuit. As it is a brand new boiler, I am reluctant to start modifying it and risk the guarantee. So if you'd bought a used 418 ecotec you'd have just what you need. There is one option that may work in some cases: reduce the maximum power output the boiler is allowed to deliver. Then you get efficiency from modulation & cycling with pump overrun becomes acceptable. NT |
how hot do you run you CH boiler
On 13/01/2019 10:58, dennis@home wrote:
On 12/01/2019 22:19, John Rumm wrote: I have though, my eye on a 470 complete with the outdoor sensor. You would probably need the VR61 or similar as well to connect to the zone valves. Better be quick.. The VR61 is obsolete and in clearance on most sites. I don't see an alternative on the valiant site. Yup the VR470 has been superseded as well. A VRT350 looks like a replacement if you don't need the weather compensation. The VR65 looks like a possible replacements for the 61. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
how hot do you run you CH boiler
Look at the Honeywell Evohome system http://www.heatingcontrols.honeywell.../evohome-Main/ The site exists, but not with the www. -- Graham. %Profound_observation% |
how hot do you run you CH boiler
On 13/01/2019 15:00, John Rumm wrote:
On 13/01/2019 10:58, dennis@home wrote: On 12/01/2019 22:19, John Rumm wrote: I have though, my eye on a 470 complete with the outdoor sensor. You would probably need the VR61 or similar as well to connect to the zone valves. Better be quick.. The VR61 is obsolete and in clearance on most sites. I don't see an alternative on the valiant site. Yup the VR470 has been superseded as well. A VRT350 looks like a replacement if you don't need the weather compensation. The VR65 looks like a possible replacements for the 61. none of it did what I wanted.. just two boiler ons with individual temperature control. I have seven dual port valves and I want them controlled by timer stats. I took the easy route and wire or'd the end switches and no additional panel for the boiler. |
how hot do you run you CH boiler
On 12/01/2019 13:54, Max Demian wrote:
On 12/01/2019 10:19, RJH wrote: On 11/01/2019 23:33, Max Demian wrote: On 11/01/2019 18:52, tim... wrote: I had a new Combi fitted today (in the to-be-moved-to house). Fitters told me that I should run this at 74 degrees. Which I thought far too high, as 1) it makes the radiators too hot to touch 2) basic thermodynamics suggest that a better temperature profile will result from having the radiators at the lower temperate for longer period than a higher temperature for a shorter period I tried to explain this but was met with "The recommended temperature is required for the condenser to have any effect" The instruction manual for my Ideal says that the 'e' setting is best for condensing, which is quite hot. I don't understand this as I would have thought that the cooler the returning water temperature the more condensing. Just found the manual for my Ideal Logic: "The Logic + Combi is a high efficiency combination boiler which is most efficient when operating in condensing mode. The boiler will operate in this mode if the CH temperature control (C) is set to the €˜e position (economy mode) or below. This control should be set to a maximum for very cold periods". I downloaded the manual and it omits the critical "or below". How odd. I've sent you my version of the manual - 2010 I think. -- Cheers, Rob |
| All times are GMT +1. The time now is 03:33 AM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter