Heating controller

R

rahman

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Will be installing solar panels and a condensing oil boiler linked to a buffer tank. I will also have 2 UFH circuits and DHW offf the buffer tank.
Is it possible to have 1 single controller for this system or will I need a seperate one for the solar.
 
Hi rahman,

I know this doesn't answer your question re. single controller, but for what it's worth.... this is exactly the setup I have, though I also have a stove/back boiler heating the buffer tank in addition to condensing oil boiler. In my case there is a separate controller for each UFH manifold and also a separate controller for solar. Solar feeds bottom coil of DHW cylinder and as far as I can tell the solar controller is very simple and just turns on solar pump when it detects temp of water in panels being 7degrees higher than temp at bottom of cylinder. There is a small LCD display on the solar controller which shows these 2 temps and also the cumultive hours that the solar pump has kicked in.

UFH controllers (heatmiser) are pretty dumb too since most of intelligence appears to be in the room stats (heatmiser). In my setup the UFH controller activates a motorised valve and the heating circulation pump whenever any of the stats on the controller call for heat. The auxilliary live from the motorised valve then activates the oil burner/pump via a stat on the buffer tank (to set desired buffer tank temp) and also a delay switch (to reduce number of on/off cycles for the oil burner).

DHW cylinder top coil is fed from buffer tank via motorised valve which is controller by a 7 day timer (Horstmann). DHW cylinder has a stat midway (bath setting) and at the top (sink setting) which allows the quantity and temp of water to be heated from buffer tank to be tuned.

Lots of discrete control parts as you can see but it seems to make sense. It would be nice though to have some single centralised controller which could be easier to operate and perhaps more effective/efficient.
It would be interesting to see what response you get because I wouldn't be adverse to changing the control system further down the line to get more efficiency, operability, etc.

Cheers
James
 
Ennisjim
thanks for the info. Seem like you have 2 tanks then with a seperate DHW tank. correct me if I'm wrong!!!!
My plan is to install a stratified buffer tank whereby water charged from the solar panel heats the buffer in the correct location within the tank. So there is a bit more control required. I have received a quotation from a crowd in cork Genertec (no connection) but the price for the package ( stratified tank, solar panels & integrated controller) is scandalous looking for 15K.
However it is the way to go having a good controller/s when using solar and oil as the heat sources. I've seen a good few threads on this forum re cost of UFH and really it all boils (no pun intended!!) to having the proper controller in place so that everything is working together. I've seen too many UFh systems connected directly to the boiler and it just doesn't work that well.
As I've yet to install my system I'm hoping that I can find the best solution
 
Yes rahman, I've two tanks. 500litre buffer and 300litre DHW cylinder. I Won't you need a DHW tank somewhere since I believe it is not normal to 'consume' the same hot water (showers, taps..) that the heating system uses ? Perhaps you are considering the 'tank in tank' approach where the DHW tank is contained within the buffer tank. These were explained to me recently and sound like a good idea. Need a pretty big tank though I suppose, eg. 800 to 1000 litre.
 
If your using the Heatmiser stats there is one that does one zone and DHW.

So the part list would be

Touchpad (optional for convenience)
Stat for each zone one of which would have DHW timings
UH1 wiring centre
zonevalves actuators

With the buffer tank and the UH1 you would wire the boiler enable from the UH1 to the stat on buffer tank then to burner. This should be easier wiring and no need to use the auxilliary wires as Ennisjim has done.

You therefore only have to use the stats or touchpad for programming and there would be no need for a seperate clock for the DHW. The UH1 provides for a seperate DHW pump and cylinder stat so it will only look to enable the boiler (through the buffer) when the solar hasn't brought it up to temp. That DHW pump would be between the coils on the buffer and the DHW cylinder.
 
Hi davidoco, unfortunately I wasn't able to use the Heatmiser stat which also controls the DHW because I am using floor sensors which limit the temperature of UFH delivered to floor. This is (i) to avoid overheating floor and damaging flooring, timber, etc and (ii) to avoid stat calling for heat when the air sensor is cooled by a draught (eg. open door/window) while floor temp is still good.

So if you use floor limit sensors with Heatmiser stats you cannot use the version with integrated DHW control. For DHW control a separate time clock was needed.

Re. the touchpad... It is optional but really worth while having. The ability to see the status (temp, etc) for every room from one location is great. Also ability to remotely keylock the stats, see history for each stat, set holiday mode, etc, etc.
 
ennisjim said:
For DHW control a separate time clock was needed.
Click to expand...

I think that the Heatmiser TM1-N in Mode 2 or 3 would have taken the place of your Horstmann for DHW and also gives the added benefit of being linked to the touchpad as a DHW zone.
 
Yes that would have been nice - didn't know about it (or more to the point my heating contractor must not have known about it). On the other hand I have 2 other channels on Horstmann for 2 radiator zones (insulated attic spaces), though there could have been a Heatmiser solution for that I guess. Would have been nice to have all controls from touchpad.
 
yes the buffer tank has a DHW coil in it which heats the water as it passes through the buffer. I will then connect the 2 UFH cicrcuits directly to the buffer. Basically I want a controller that will allow me to control the 2 UFH circuits and not allow the boiler to come on every time a room stat calls for heat.
davidoco
could you pm me where I could get these controllers as you have described
 
rahman said:
yes the buffer tank has a DHW coil in it which heats the water as it passes through the buffer. I will then connect the 2 UFH cicrcuits directly to the buffer. Basically I want a controller that will allow me to control the 2 UFH circuits and not allow the boiler to come on every time a room stat calls for heat.
davidoco
could you pm me where I could get these controllers as you have described
Click to expand...
Hi rahman, this is what the delay switch is supposed to help with. I think the idea is that when a room calls for heat the UFH controller (Heatmiser UH1) opens the actuator, activates the boiler (and a motorised valve) but the boiler activation goes via buffer tank stat and finally the delay switch. My heating contractor explained the settings to me recently... The delay switch is to be set to 20 minutes and buffer tank stat to 65 degrees. The delay switch means that the boiler will come on 20 minutes after the UFH calls for heat. In the meantime the UFH system will draw the water (which will probably be at 65) and use it, cooling it down as heat goes into floor. Then after 20 minutes the boiler kicks in and starts to heat buffer tank back up to 65 while at same time the UFH system draws water.
This is the theory - I don't know how well it will work in practice since I haven't moved in yet and am running system on 'holiday mode', ie. all stats set to 12degrees. Also delay switch currently set to zero but will try the 20 minute setting in next few days and see how it goes.
 
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