New two channel programmer, heating not coming on

[Johnny2R]

@Stuckinarut , sorry, wasn't you I meant to quote there but @cider !

 

[Johnny2R]

Tried ringing Danfoss tech support but they don't provide support for home owners! This is getting very frustrating.

 

[Johnny2R]

Finally got an answer from Danfoss to my e-mail. They just sent me the User Guide! As if I hadn't already looked at that! My God, this is getting frustrating...

 

[CountryFan]

Finally got an answer from Danfoss to my e-mail. They just sent me the User Guide! As if I hadn't already looked at that! My God, this is getting frustrating...

Personally then if there's no jumpers on the back just take it back as faulty.

 

[Johnny2R]

Well, I've got the customer service people to forward the question to technical now. Their answer will mean either that I can use the device as planned or that I will have something definitive to go back to the supplier with, to show that it doesn't do what it says on the website. (To be fair, the fact that this copy is used on a number of websites suggests that it comes from Danfoss themselves, which is a bit of a whoopsy if it turns out to be wrong).

 

[CountryFan]

. (To be fair, the fact that this copy is used on a number of websites suggests that it comes from Danfoss themselves, which is a bit of a whoopsy if it turns out to be wrong).

Well, to be fair to Danfoss, it's not actually quoted on their website, but maybe it was changed and suppliers didn't get the memo?

 

[Johnny2R]

No, it isn't, but the shared copy across supplier websites does suggest it's something Danfoss themselves have put out.

The blasted nuisance now is that if I have to send the item back to the supplier, I will presumably also have to send back the backplate, which will mean rewiring which I had hoped to avoid (the handy ability to just clip in a new programmer to an industry standard backplate is only relevant if the backplate remains in place).

 

[CountryFan]

Not necessarily, if you find out that it's incompatible and you can get a programmer and backplate the same colour, maybe send that back?

 

[Johnny2R]

Yes, maybe. Don't want to have to get the electrician out again, but the rewiring is probably too fiddly for me to do.

 

[ericmark]

Switch, slide, or software will stop you selecting an invalid option. But the programmer should still work with valid options.

But it does seem the FP720 is not designed to work with C Plan.

So would be interesting to see where is says it will work.

As to the electrician, I consider what I would likely do. I would have I hoped pointed out not suitable, but not sure I would have wanted to mess around programming a unit I don't normally fit, I would have possibility connected up and left to customer so set up.

I have not fitted a programmer in years, they have been replaced with the programmable thermostat, which will allow different temperatures through the day, when the energy saving light bulb came out, the radiant heat from the tungsten bulb was lost, so I have wanted to set daytime at a lower temperature to evening, so started to use programmable thermostats.

I would have likely fitted Hive which does have the option to work with C Plan. But where we are given a thermostat to fit, we have to basic do as we are told. Nest Gen 3 would also work, Wiser likely would not work, not sure about EvoHome or Tado.

 

[cider]

So should the central heating actually work as long as the hot water is on?

Yes. Basically the hot water on runs power to the boiler. The boiler gets hot and water gravitates to the cylinder. No wizardry
Heating on runs the pump via the room stat.
If you had the correct programmer then whenever you put the heating on, the hot water output is automatically triggered as well to turn the boiler on (which yes will also still heat your cylinder wether it needed or not). Setting your heating on to the same time as your hot water will solve your problem.
The old mechanical timers used to have the selectors locked together in gravity hw mode. When you slid the heating along to timed etc it forced the hw one along as well to run the boiler.

 

[DP]

Yes, I did try turning up the thermostat to the highest temperature, without any effect. But surely the fact that the pump has kicked in is an indication that the system is responding to demand, but it's just not working right because the boiler isn't firing up? Presumably if it was the case that the room temperature was already high enough, the pump wouldn't run? (I think this is what @DP is saying, too).

In dim past often the cylinder was near the back boiler and connection often was 28mm boiler to cylinder and coil in the cylinder was a few turns such that heated water in the boiler needed no mechanical propulsion to heat the water

For heating the timer ran the pump

The boiler did not switch on so an internal timer link was activated for gravity option that fired the pump

Fast forward to turn of the century, higher fuel costs and boiler now controlled by microcontrollers and aiming for maximum, clunky slow heating of water in the cylinder devoid of any cylindrical thermostats using minimal heat transfer to water is out of the window.
Now both heating and hot water have independent zones and often can be programmed for differing Sime slots.

What you have, can still be modified
Installing a programmable thermostat can be wired to enable the function you had require
Also fitting a 28mm zone valve to cylinder primary will also enable the system to work with better hot water t3mperature control.

In a nutshell, wiring option exists that will allow the system work

 

[ericmark]

I am advised by my heating guy, that my boiler needs to cool when switched off, and it does this by heating the domestic hot water (DHW) both C Plan and Y Plan allow this, but Y Plan will allow central heating (CH) only so the DHW can be set to a lower temperature, but the default valve position is DHW so any excess heat can go into the DHW.

It would be easy to install a relay, so when the pump runs it also runs boiler, however the cost of a box for the relay and wiring is likely more than the cost of the programmer, and in this day and age I see no point in separate programmer and thermostat, the programmable thermostat has made programmers obsolete.

Today there are two methods to heat the home, 24/7 for every room and super insulated home, common to use under floor heating and/or a heat pump, or heat only when the room requires it, the latter normally using thermostatic radiator valves (TRV) which with electronic heads can also be programmed as to when to heat the room.

However if for example a bedroom is only heated at 10 pm to 6 am, for that TRV to control the room, the boiler must clearly run, so if you have say 4 bedrooms then one bedroom needs to be able to fire the boiler and pump. This could be a wall thermostat in the bedroom, but could also be a linked TRV head, and this is what the likes of Hive does.

The result is the most important part of the CH control is the TRV, with some claiming to work out how long it takes to heat the room, so they turn on that amount of time before the time set for room to be to temperature, I know Drayton Wiser heads do that.

But it does seem there is no one system that will do all, and at £59 for the Hive TRV head, around £45 for Wiser head, one has to look at the total cost, I started in around 2019 in this house, and at that time the non linked bluetooth eQ-3 TRV heads cost me £15 each, post Brexit the price went up, there is also the Terrier i30 which does not link, but at the time they did not have any way to link to phone.

I brought with me to the house 4 Energenie TRV heads, Wi-Fi linked from my late mothers house, but the thermostat that worked with them had to be hard wired, and I only had two wires main house to boiler, so I was told Nest would also work with them, so got Nest, it seems when Nest was taken over by Google the ability to work with Energenie went, so last year I lashed out and fitted Drayton Wiser in parallel to the Nest, so Nest is only way to run boiler only for DHW, but Wiser can run boiler and pump when required to heat coolest bedroom and living room.

At long last the heating works well, I wanted to ensure all was electrical powered from one point, as I have batteries and solar, which means with a power cut, my heating still works. But also I have found that heating DHW is far cheaper using electric to oil in the summer, the DHW can't be turned off with C Plan so winter it is heated using the oil boiler, only when the CH is running, but summer I use the immersion heater.

I made a mistake getting iboost+ but what it does do is tell me how much energy I have used in last week, and it is never over 5 kWh normally 4.5 kWh or there about. I can if the immersion heater fails use the oil as back-up, and if I want a bath, then not enough heated with the immersion heater, but I no longer use oil to heat DHW in the summer.

In your position I would likely fit Hive, but I made so many errors with my house, although I maintain Nest Gen 3 was not my fault, I was miss sold it, I thought it would work with the Energenie TRV heads. If you have no intension in the future of fitting TRV heads then Nest Gen 3 would work, already given you wiring diagram.

 

[Johnny2R]

I picked up a very cheap Drayton LP722 (£20 on eBay), and have replaced the Danfoss with this, having configured the dipswitch on the back to gravity instead of pumped, so theoretically all should work fine. One minor puzzle. In the manual there is this:

"On each side of the display there are four operating modes – one group for central heating, the other for hot water. "

But for some unfathomable reason it doesn't tell you which is which, either in the manual or via a label on the device itself. I'm kind of assuming that the left-hand ones are for the hot water, as that side is where the hot water boost button is. Can anyone familiar with the Drayton LP722 confirm this?

 

[Mister Banks]

I picked up a very cheap Drayton LP722 (£20 on eBay), and have replaced the Danfoss with this, having configured the dipswitch on the back to gravity instead of pumped, so theoretically all should work fine. One minor puzzle. In the manual there is this:

"On each side of the display there are four operating modes – one group for central heating, the other for hot water. "

But for some unfathomable reason it doesn't tell you which is which, either in the manual or via a label on the device itself. I'm kind of assuming that the left-hand ones are for the hot water, as that side is where the hot water boost button is. Can anyone familiar with the Drayton LP722 confirm this?

Yes