New Boiler - Weather Compensator?
Discussion
FiF said:
I can't see the point in setting the output lower unless it's to match the output better to the demand for a small house /oversized boiler and thus avoid boiler cycling. That issue is automatically dealt with if the boiler has a fully modulating burner surely?
Pass 
As i said, i am going to give them all a call today and try and get some more detailed info.
I think WC is not really used a lot in a domestic situation, and the tech is still in its infancy.
Alucidnation said:
Pass
As i said, i am going to give them all a call today and try and get some more detailed info.
I think WC is not really used a lot in a domestic situation, and the tech is still in its infancy.
I have been fitting it as a matter of course for at least the last three years, Most of my customers don't even know that it is there.As i said, i am going to give them all a call today and try and get some more detailed info.
I think WC is not really used a lot in a domestic situation, and the tech is still in its infancy.
When I read about it being on 24x7 I just thought "no way" kids and the wife leaving windows and doors open to cool down.
I calibrated the heating system to only heat the house to the point in autumn where you think to yourself 'hmm its getting chilly' (~17c) - so over winter the house was only heated to late autumn temp and no more unless you turn it up manually. The house is modern so gets up to temperature pretty quick - so the concept of keeping the heating on all the time doesn't feel right to me.
The other change that had a big impact was setting the hysteresis of my thermostats (which are all done software) to 2'c rather than the more usual .5 or 1'c - this stops the boiler is constantly cycling all the time. The hot water cylinder has 3'c of Hysteresis - it heats up once in the morning and then stays off for the time period.
Once you get home or if you know you are due home, fire up the iphone and turn the temp up remotely:
The great thing about using automation for this is that it knows when you are away - so it turns down all the heating and locks it off.
I calibrated the heating system to only heat the house to the point in autumn where you think to yourself 'hmm its getting chilly' (~17c) - so over winter the house was only heated to late autumn temp and no more unless you turn it up manually. The house is modern so gets up to temperature pretty quick - so the concept of keeping the heating on all the time doesn't feel right to me.
The other change that had a big impact was setting the hysteresis of my thermostats (which are all done software) to 2'c rather than the more usual .5 or 1'c - this stops the boiler is constantly cycling all the time. The hot water cylinder has 3'c of Hysteresis - it heats up once in the morning and then stays off for the time period.
Once you get home or if you know you are due home, fire up the iphone and turn the temp up remotely:
The great thing about using automation for this is that it knows when you are away - so it turns down all the heating and locks it off.
eliot said:
When I read about it being on 24x7 I just thought "no way" kids and the wife leaving windows and doors open to cool down.
I calibrated the heating system to only heat the house to the point in autumn where you think to yourself 'hmm its getting chilly' (~17c) - so over winter the house was only heated to late autumn temp and no more unless you turn it up manually. The house is modern so gets up to temperature pretty quick - so the concept of keeping the heating on all the time doesn't feel right to me.
The other change that had a big impact was setting the hysteresis of my thermostats (which are all done software) to 2'c rather than the more usual .5 or 1'c - this stops the boiler is constantly cycling all the time. The hot water cylinder has 3'c of Hysteresis - it heats up once in the morning and then stays off for the time period.
Once you get home or if you know you are due home, fire up the iphone and turn the temp up remotely:
The great thing about using automation for this is that it knows when you are away - so it turns down all the heating and locks it off.
If you leave home and the app. notices and turns the heating off, what about the wife and kids? Does everyone in the house have the app. and do they all interact?I calibrated the heating system to only heat the house to the point in autumn where you think to yourself 'hmm its getting chilly' (~17c) - so over winter the house was only heated to late autumn temp and no more unless you turn it up manually. The house is modern so gets up to temperature pretty quick - so the concept of keeping the heating on all the time doesn't feel right to me.
The other change that had a big impact was setting the hysteresis of my thermostats (which are all done software) to 2'c rather than the more usual .5 or 1'c - this stops the boiler is constantly cycling all the time. The hot water cylinder has 3'c of Hysteresis - it heats up once in the morning and then stays off for the time period.
Once you get home or if you know you are due home, fire up the iphone and turn the temp up remotely:
The great thing about using automation for this is that it knows when you are away - so it turns down all the heating and locks it off.
Also if you're going to turn it on by app. before you get home then presumably you want to turn off by app before you leave home rather than wait for it to notice.
Mines a 200 year old house with crap insulation and thick walls, when the heatings off it cools quick and takes ages to heat and suffers from a few areas of damp on a couple of walls so I leave it on all day to combat all that, last year I tried it out over a month at the start of winter as we have a smart meter and there was not much difference in the cost of being on all day to coming on twice a day so I leave it on to help with the damp issues a bit but yes in a new house you probably wouldn't do it. The boiler if left in fully modulating mode will try and get up to temp quickly then modulate down which I don't need as all it has to do is top up a bit every 20 mins or so I also changed the time it stays off for between firing (longer) so it doesn't come on/off as much.
moles said:
A weather compensator as far as I can work out just brings the boiler on or off earlier/later depending on outside temps. i don't think they save you any money and a room stat works in the same way just is slower to react to the change in outside temp.
That's an optimiser. Weather compensated circuits (or variable temperature (VT) as they are also known) are common in commercial buildings on radiator circuits and are a building regulations requirement on larger systems.On a VT setup, there will be a boiler, or bank of boilers that will kick in as and when they are needed. The boilers will usually then feed a number of circuits. Domestic hot water calorifiers, fan coil units and air handling unit heater batteries will connect directly to the flow and return (sometimes by a header or heat exchanger) as constant temperature (CT) circuits. The radiator VT circuits use a three port valve to modulate the temperature. The controller monitors the outside temperature (by a sensor on a north facing wall) and the flow temperature, and will tell the valve what position it should be in.
VT technology is not new and it pre-dates condensing boilers. Older boilers (or other heat sources) could not regulate the temperature so they would always give out the same output. In winter, more heat is absorbed from the radiators, so the internal thermostat will be calling for heat more often and the time periods between the thermostat being satisfied and and calling for heat again will be shorter. When it is warmer, it will take a while for the internal temperature to drop, so that interval becomes longer. During this time, all that water in the system is cooling, and when the thermostat calls for heat again, the boiler has to work hard to get the circuit back up to temperature. By reducing the flow temperature in warmer weather, the thermostats are not switching state as often, which means more stable temperature control, reduced energy consumption and reduced wear on plant. As controls become more sophisticated (variable output motors, variable speed motors etc), the three port valve method is becoming less common, but the end result is similar.
If the technology is there, I can see a good reason for manufacturers to introduce it on new boilers. I'm not sure how they do it on domestic systems, but I would expect it would be by modulating the burner rather then a three-port valve arrangement. You will still need indoor thermostats or temperature sensors.
There will certainly be energy savings from this type of boiler, but I'm not so sure they would offset any additional cost. I'd expect in time the technology will be more common and cost difference to drop.
Ganglandboss said:
moles said:
A weather compensator as far as I can work out just brings the boiler on or off earlier/later depending on outside temps. i don't think they save you any money and a room stat works in the same way just is slower to react to the change in outside temp.
That's an optimiser. Weather compensated circuits (or variable temperature (VT) as they are also known) are common in commercial buildings on radiator circuits and are a building regulations requirement on larger systems.On a VT setup, there will be a boiler, or bank of boilers that will kick in as and when they are needed. The boilers will usually then feed a number of circuits. Domestic hot water calorifiers, fan coil units and air handling unit heater batteries will connect directly to the flow and return (sometimes by a header or heat exchanger) as constant temperature (CT) circuits. The radiator VT circuits use a three port valve to modulate the temperature. The controller monitors the outside temperature (by a sensor on a north facing wall) and the flow temperature, and will tell the valve what position it should be in.
VT technology is not new and it pre-dates condensing boilers. Older boilers (or other heat sources) could not regulate the temperature so they would always give out the same output. In winter, more heat is absorbed from the radiators, so the internal thermostat will be calling for heat more often and the time periods between the thermostat being satisfied and and calling for heat again will be shorter. When it is warmer, it will take a while for the internal temperature to drop, so that interval becomes longer. During this time, all that water in the system is cooling, and when the thermostat calls for heat again, the boiler has to work hard to get the circuit back up to temperature. By reducing the flow temperature in warmer weather, the thermostats are not switching state as often, which means more stable temperature control, reduced energy consumption and reduced wear on plant. As controls become more sophisticated (variable output motors, variable speed motors etc), the three port valve method is becoming less common, but the end result is similar.
If the technology is there, I can see a good reason for manufacturers to introduce it on new boilers. I'm not sure how they do it on domestic systems, but I would expect it would be by modulating the burner rather then a three-port valve arrangement. You will still need indoor thermostats or temperature sensors.
There will certainly be energy savings from this type of boiler, but I'm not so sure they would offset any additional cost. I'd expect in time the technology will be more common and cost difference to drop.
SS
Ganglandboss said:
moles said:
A weather compensator as far as I can work out just brings the boiler on or off earlier/later depending on outside temps. i don't think they save you any money and a room stat works in the same way just is slower to react to the change in outside temp.
That's an optimiser. Weather compensated circuits (or variable temperature (VT) as they are also known) are common in commercial buildings on radiator circuits and are a building regulations requirement on larger systems.On a VT setup, there will be a boiler, or bank of boilers that will kick in as and when they are needed. The boilers will usually then feed a number of circuits. Domestic hot water calorifiers, fan coil units and air handling unit heater batteries will connect directly to the flow and return (sometimes by a header or heat exchanger) as constant temperature (CT) circuits. The radiator VT circuits use a three port valve to modulate the temperature. The controller monitors the outside temperature (by a sensor on a north facing wall) and the flow temperature, and will tell the valve what position it should be in.
VT technology is not new and it pre-dates condensing boilers. Older boilers (or other heat sources) could not regulate the temperature so they would always give out the same output. In winter, more heat is absorbed from the radiators, so the internal thermostat will be calling for heat more often and the time periods between the thermostat being satisfied and and calling for heat again will be shorter. When it is warmer, it will take a while for the internal temperature to drop, so that interval becomes longer. During this time, all that water in the system is cooling, and when the thermostat calls for heat again, the boiler has to work hard to get the circuit back up to temperature. By reducing the flow temperature in warmer weather, the thermostats are not switching state as often, which means more stable temperature control, reduced energy consumption and reduced wear on plant. As controls become more sophisticated (variable output motors, variable speed motors etc), the three port valve method is becoming less common, but the end result is similar.
If the technology is there, I can see a good reason for manufacturers to introduce it on new boilers. I'm not sure how they do it on domestic systems, but I would expect it would be by modulating the burner rather then a three-port valve arrangement. You will still need indoor thermostats or temperature sensors.
There will certainly be energy savings from this type of boiler, but I'm not so sure they would offset any additional cost. I'd expect in time the technology will be more common and cost difference to drop.
SS
silversurfer1 said:
So does that 3 port valve mix return water with the flow water to create the VT circuit ? if so i guess it reverses the flow through the bypass dragging return water back up it?
SS
The diagram is from a very concise textbook I have, and is wrong. I was doing an HNC in construction and property and they would not give me an exemption from the building services module and that book was on the reading list. It is a compensated circuit, but it is variable flow rather than a variable temperature. These are from the Spirax Sarco website (controls manufacturer):SS
The above is a constant flow variable temperature loop. The loop on the right is the radiator circuit and you can see the pump is in that loop. The pump draws hot water from the port marked AB. Depending on the position of the valve, it will either draw it from port A (hot water from the boiler) or port B where it recirculates the water from the return.
The valve is driven by an actuator. Pneumatic actuators are becoming more common, but older valves had motors that drove a hydraulic pump. The pump would drive the valve to one position and a solenoid would open to return, allowing a heavy spring to push the valve back. Usually it would have a 24v a.c. supply to the pump and a 24v supply to the solenoid, meaning it was in one position or the other, however, some had a variable resistor that moved relative to the position of the valve, allowing the controller to sense the position according to the reading fed back and stop the valve in any position between the two ports. More modern actuators and controllers have a 24v permanent supply to drive the motor and solenoid, but give the valve a 0-10v d.c. reference voltage to tell it what position it should be in (1v = 10% open, 4v = 40% ect.).
This one is a variable flow constant temperature. There is no pump in the radiator circuit. The pump draws hot water from the boiler and into port AB. The three port valve opens port A more to feed more to the radiator circuit, or less to allow hot water to flow to port B and back to the boiler, thus reducing the flow rate in the radiator loop.
Well, had the wc system in for over a week now and works quite well as far as I can tell, as it's not exactly been cold!
A few issues with the existing system to start with, as in all the zone valves needed replacing but as things go, it was fairly painless. All the trvs were changed for Danfoss liquid filled and seem responsive, more so than the traditional wax type, although I see that they now do gas filled which should be even better.
The room stats still give overall total control over the system, but I think at some point they will be removed.
The viessman boiler is extremely quite once it has settled down and the display gives the flow temp through the boiler.
This alters as the external temps change and increases as it gets colder.
So, all in all, looking good so far, although I'll still reserve judgement until the winter!
A few issues with the existing system to start with, as in all the zone valves needed replacing but as things go, it was fairly painless. All the trvs were changed for Danfoss liquid filled and seem responsive, more so than the traditional wax type, although I see that they now do gas filled which should be even better.
The room stats still give overall total control over the system, but I think at some point they will be removed.
The viessman boiler is extremely quite once it has settled down and the display gives the flow temp through the boiler.
This alters as the external temps change and increases as it gets colder.
So, all in all, looking good so far, although I'll still reserve judgement until the winter!
Quick update!
After now having the heating on for a few days now the evenings are getting a bit colder, i have left it running 24/7 on the factory set curve.
The house is now an even temperature throughout after having tweaked the TRV's for each room, using some basic thermometers bought from Amazon to get a rough idea. All rooms are around the 20-21C and very comfortable. Its nice getting up in the night for a pee in to a warmer house.
For the last few days i have been in and out at various times and the temp has been very stable with the boiler adjusting well to the changes in external temps.
It was a bit of a faff to set up but, in my opinion and experience, well worth it!!
Over and out.
After now having the heating on for a few days now the evenings are getting a bit colder, i have left it running 24/7 on the factory set curve.
The house is now an even temperature throughout after having tweaked the TRV's for each room, using some basic thermometers bought from Amazon to get a rough idea. All rooms are around the 20-21C and very comfortable. Its nice getting up in the night for a pee in to a warmer house.
For the last few days i have been in and out at various times and the temp has been very stable with the boiler adjusting well to the changes in external temps.
It was a bit of a faff to set up but, in my opinion and experience, well worth it!!
Over and out.
We have an ideal logic+ combi on two heating zones, downstairs and upstairs with a weather compensator and it uses very little gas, bill for last month keeping the whole place at 20'c was £31 including showers and whatnot. Not sure how much the WC has to do with it but I was mighty pleased with that.
herewego said:
What a ridiculous waste of fuel to heat your house 24 hours a day.
Just had a WB boiler and their Wave controller fitted to daughter's house.Tried the weather comp and I was bemused that it causes the pump to run all the time regardless of the room temp setting (although there is a setting which will turn it off at night).
I thought there was something wrong, but some Googling and confirmation from WB is that these systems are "constant circulation" and they work by measuring the water flow temp and comparing that to the outside temp.
I can kind of see how that's a good idea for underfloor heating which is slow to respond, but as stated above, it seems ridiculous in a radiator system to have the water circulating and keep heating it now and again to keep it tepid.
herewego said:
What a ridiculous waste of fuel to heat your house 24 hours a day.
What experience of a weather compensated system do you have?I chose this particular system as the house is occupied most days, and from after having used it for a while, find that it keeps the internal temperature very stable, regardless of outside temps.
We like a warm environment, but hated using a room stat as they were so unreliable and to be honest, i am very surprised at how well it all works.
As for cost, well, I'm reckoning that it will cost the same, if not a bit less to run, than the old system.
mrorange26 said:
Could you pm the sensor viessmann use thanks
I cant find it in my notes now. I found a document that had the temperature / resistance curve for the actual sensor and it's just a standard off the shelf thermistor, so then I just searched for sensors that had a matching curve. Sensor was about £3 I think!Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff