ELV (12 volt DC ) operated zone valves

[looneyfitter]

Why not use the viessmann 200w as suggested? Fantastic piece of kit.

You could also fit Prog room stats in each room, (heatmiser for example) (runs over cat 5), and fit 240v acuators at each radiator and build a small LV box with a 240/12v relay in it situated close by. You would then be able to run the 12v signal (SL) over cat5 or 12v bell wire (dependant on length of run). More than likely have to build a multiple 240/12v relay box at the controller to switch from 240 to 12v/24v.

Would be very cheap to run and set up and best of all, all off the shelf..

Just another idea HTH

 

[Onetap]

Cartel ? possibly but greed for profits and the idea of making repairs almost as expensive as new system to market more equipment .

Boiler PCBs are used in all domestic boilers, despite the high replacement costs; there is no alternative if one is to achieve the efficiency, safety and reliability requirements.

BMS electronic controls are virtually unknown in the domestic market; the average installation uses 19th century electro-mechanical thermostats and on/off control valves; utter madness, given the approaching energy famine.

True but they are working to a marketing requirement to sell as many ssytems as possible. This means most of the designs are aimed at meeting the needs of the most common type of house. It is un-economic to make them capable of meeting the needs of the unusual houses.

The opposite is true; the controllers are intended to control generic office buildings, no two of which are the same. The design process uses cut & paste of standard control strategies for each plant item.

10-12 analogue inputs, 10 analogue outputs (3-point control, no end limit switches required), set up alarms (the same control for each of the 8-10 rooms) frost strategy, 2 or 3 digital outputs for pumps. Most of the work would be in wiring and asssembling the enclosure.

 

[mysteryman]

Yes, but it's still on-off control of a constant temperature boiler.

Crazy, when you can get everything plug-and-play from one manufacturer off the shelf.

 

[bernardgreen]

You could also fit Prog room stats in each room,

And have to program them individually when it is necessary to change the on-off times and/or temperature settings. A temperature sensor in each room reporting to a central pocessor will allow all time and temperature changes to be made from one location and allow for such changes to be performed automatically.

and fit 240v acuators at each radiator and build a small LV box with a 240/12v relay in it situated close by.

The reason for using 12 volt actuators is to remove the need for 230 volts at the valve locations.

Boiler PCBs are used in all domestic boilers, despite the high replacement costs; there is no alternative if one is to achieve the efficiency, safety and reliability requirements.

Agreed they are the only viable way to achieve the necessary function but that is no excuse for them to be badly designed, poorly assembled and as spare parts over priced. In one design the soldered connections to the sockets on the PCB were subjected to vibration from the cable loom ( fan and burner being the sources of the vibration )which together with poor flow soldering meant the joints failed prematurely. Poor soldering because the large pins of the sockets were being soldered at the same time as surface mounted miniature electronic components. If the solder was hot enough and applied long enough to make good joints onto the pins then it meant the components were over heated. Restricting the heat and time to the safe maximum for the components meant the soldering of the pins was inadequate. In the new design the cables are "restrained" to prevent vibration reaching the PCB and the connections of the loom to the PCB are hand soldered after the components have been soldered.

 

[looneyfitter]

Heatmiser stuff can be controlled from a central pad. Also I'm sure they do a 12v actuator. Why don't you want 240 at the valve?

 

[bernardgreen]

Heatmiser stuff can be controlled from a central pad. Also I'm sure they do a 12v actuator. Why don't you want 240 at the valve?

It is a thatched cottage and all mains wiring above the thatch line has to be in copper sheathed cable or in non flexible steel conduit.

 

[looneyfitter]

240v could be taken from a spur/socket already in the room

Also could you not repipe the rads to a central manifold below the roofline and control from there? Have a look argue heatmiser plus system, it's spot on, have it running in my own home with the vitoden 200w and wc. Highly recommended. Also give the ability to control your heating from your phone etc or even txt

 

[gasafengineer]

Interesting thread , seems most are concerned with heat output rate using water flow rate as opposed to variation of heat output rate via flow temperature , the latter being the most effective due to 'outdoor temperature modulation , maybe something to consider?

 

[mysteryman]

The choice is between efficient simplicity off the shelf, or an impressive array of gizmos.

 

[Norcon]

weather compensation and trv's with remote sensors.

 

[looneyfitter]

Interesting thread , seems most are concerned with heat output rate using water flow rate as opposed to variation of heat output rate via flow temperature , the latter being the most effective due to 'outdoor temperature modulation , maybe something to consider?

Weather compensation has already been suggested.

Individual programmable room stats are much more effective than trvs with remote probes too.

 

[Norcon]

Individual programmable room stats are much more effective than trvs with remote probes too.

A simple stat is on/off. A trv is proportional control and it has on/off also.
That makes the trv more effective.

 

[Onetap]

Individual programmable room stats are much more effective than trvs with remote probes too.

A simple stat is on/off. A trv is proportional control and it has on/off also.
That makes the trv more effective.

A room sensor and a modulating two port valve is proportional control, or can be, like the TRV. It can also be PID (Proportional, Integral and Derivative) control, if you like that sort of thing. Or it could do on/off, temperature control, like the thermostat. And it's on/off too, by remote control, by time zone, by optimum start/stop, by frost protection over-ride. With data logging of the room temperature. And remote monitoring of room temperature hi/lo alarms. And with timed exercising of the actuator when not in use. Et cetera, et cetera.

 

[monoxide62]

A room sensor and a modulating two port valve is proportional control, or can be, like the TRV. It can also be PID (Proportional, Integral and Derivative) control, if you like that sort of thing. Or it could do on/off, temperature control, like the thermostat. And it's on/off too, by remote control, by time zone, by optimum start/stop, by frost protection over-ride. With data logging of the room temperature. And remote monitoring of room temperature hi/lo alarms. And with timed exercising of the actuator when not in use. Et cetera, et cetera.

Also known as highly non-linear , large reductions in water flow rate results in only a small reduction in heat output rate only becoming more linear as design flow & return temperature differential is increased. Only expensive valves are available that will produce large reductions in flow rate for small valve stem movement (commercial) , these type valves are normally used to control a number of emitters as opposed to individual control , cost being the major factor.

 

[looneyfitter]

Individual programmable room stats are much more effective than trvs with remote probes too.

A simple stat is on/off. A trv is proportional control and it has on/off also.
That makes the trv more effective.

Trvs are also very slow to react!! Digital prog room stats are a much better option IMHO giving a fair bit more control to the customer. Not to mention optimisation.