Danfoss TP5000 not "communicating" with Heatrae Sadia Electromax

[TimBridle]

Danfoss TP5000 not "communicating" with Heatrae Sadia Electromax.

Hi everyone, first post here, so I hope this is in the correct forum. I recently moved into a house with a Heatrae Sadia Electromax boiler, controlled by a Danfoss TP5000 thermostat. Everything seemed to be fine for the first couple of months, when the weather was warm, but now we're heading into winter and I'm realising that, actually, something's awry. The boiler for the central heating is coming on at the same time, every day, seven days a week, despite the fact that the thermostat is programmed for six time schedules during the week, and six different time schedules for the weekend. Without fail, every day at 1:30pm until 4pm the heating comes on, then again from 8pm until just before 10pm. I almost thought maybe the thermostat wasn't connected to the boiler at all, but when the heating is on I can reduce the thermostat temperature and the heating does go off, so there is that.

I've tried replacing the batteries, to no avail. I've also removed the batteries for several minutes, in case it needed a full reset. I've tried the manual reset from the control panel itself, (using a button combo - mine doesn't have a recessed reset button), but none of this has worked. I don't seem to be able to get to the User Advanced Settings screens. I press and hold PROG and V for three seconds, but all it does as soon as I press the buttons is it goes into programming mode, where it's offering me the chance to change the time of day.

Unfortunately I don't have any manuals from the previous home owners, so I'm assuming that the boiler programming is somehow set at the boiler itself, and the thermostat is simply working as a temperature regulator for the short times the boiler is on. However, I can't identify any such settings on the boiler.

Have raised the question with Heatrae Sadia, but thought I'd also ask here in case anyone with knowledge of this setup has any advice.

Many thanks.

 

[Basher]

Sorry I don't have intimate knowledge of your specific programmable stat, but am familiar with similar systems.

You may know that the user manuals (and the installation manuals) for your stat and boiler are freely available on the internet.
I wasn't going to include a link as I'm not sure exactly which version of the thermostat you have (TP5000 Si?)
But here's the current one, maybe not yours?

https://assets.danfoss.com/documents/47184/AN000086406036en-010201.pdf

The fact that turning the temp. down on the room stat does turn the heating off, shows the thermostat is operating the boiler. I think it's just a hard wired single pole switch in the stat that activates the heating circuit, so not much to go wrong!

The Electromax is basically a big storage tank of water, that is heated by Economy 7 electricity overnight (and if necessary by 'full price' electricity during the day by pressing the 'boost' button).
The heating of the tank every night should be happening irrespective of the setting of the programmable thermostat, and is not affected by the thermostat clock etc.

Stating the obvious - the programmable stat is set to when you want the radiators to come on, and it basically just turns on a pump that circulates the water through the radiators and back to the tank. It seems a previous owner has set the two periods to 13.30 - 16.00 and 20.00 - 22.00, which is a bit odd, and several of those times are not exactly the pre-set options in the stat. so presumably have been edited manually.

If you can find user instructions for your thermostat on the web that exactly correspond to the model you have (which you say doesn't have the reset 'hole' to stick a pin in?), you may be able to get further with the settings
I've just noticed, for the current model, there's a switch inside the unit that enables and disables 'reset', to be set by the installer. That might be why you can't reset it!

Otherwise you might consider spending £32 on a like for like replacement, and just swap it over (power off while you do it!).
Hopefully a new one would respond as described in the literature!

 

[TimBridle]

Sorry I don't have intimate knowledge of your specific programmable stat, but am familiar with similar systems.

Thanks for the response, and apologies for the delay in my reply. The Heatrae Sadia Electromax itself has been playing up lately, so the TP5000 programming issue has been the least of my worries.

I've since realised that the heating will come on at midnight, as well as the 1:30pm to 4pm and 8pm to 9:50pm timings I mentioned previously, and I've realised that these are likely the off-peak times for the area in which I live. (I read somewhere that, for the UK at least, off-peak is 1pm to 4pm, 8pm to 10pm and midnight to 5am. I've not sat up all night to watch the boiler, but these do seem to relate very closely to the times my boiler will heat the radiators.)

The alarm light on the boiler has come on a few times in the last couple of months, but a "turn it off and on again" has usually solved this. Then I realised it was probably happening because the pressure in the system was too low, so I topped that up and got it working again, only for it to raise the alarm again the next day, or for it to simply not bother to heat the radiators, even when the "Demand" light is lit.

After multiple attempts to get it working yesterday, I switched off the Hot Water switch on the Electromax and the heating then decided it was going to work, so at least I might avoid freezing this Christmas! But an engineer is booked for early in the new year. Heatrae Sadia weren't really able to help, since they say the boiler has obsolete parts...even though it's only around ten years old. (They don't make things like they used to!)

 

[Basher]

Thanks for the update. I hope the engineer sorts it to your satisfaction.

I admit I hadn't understood the operation of the Electromax.
I now see it heats the cylinder of hot water on night rate, and heats the radiators with a separate element when you need, not as I thought using stored heat in the cylinder.
The 'boiler' part is an instantaneous water heater for the radiators.

https://mediacdn.heatraesadia.com/-/media/themes/heatrae/literature/installation-manuals/electromax_7031656_issue_10.pdf?v=1&d=20190731T132440Z

As you say, the clock/timer in your programmable stat is not doing what it's supposed to.
I believe the boiler does not have a programmer or timer in it, just safety circuitry, so it's not clear to me why it's coming on at all, if it's not being controled by the programmable stat.
I would have expected it to come on only when the control voltage from the stat is active.

As you say, Economy10 is generally set for midnight–5.00am; 1.00pm–4.00pm; and 8.00 pm–10.00 pm, which ties up with when your boiler comes on. It might be that the previous owner of the house decided to run the boiler just from E10, and the control wiring has been modified to make the boiler come on whenever the E10 power is applied.
Do your electricity bills show you are on the E10 dual rate?

Hopefully it will all be clear when the engineer has a look!

(A lot of spares, including elements and circuit boards, seem to be still available)

 

[TimBridle]

Thanks for the update. I hope the engineer sorts it to your satisfaction.

I hope so too, thanks.

My electricity bill does say "Standard Economy 10", so that part is at least correct. However, this got me thinking :- there are four wires going into the right side of the Electromax. One is the main on/off cable, and if I turn this off the whole thing goes off, obviously. There's an un-switched cable which is from the thermostat. There's a switched labelled "Off-Peak Hot Water", and there's an illuminated orange switch labelled "Off-Peak Heating". Now, the illuminated orange light on the "Off-Peak Heating" switch only ever comes on during off-peak times, which makes sense. But because of this, it occurs to me that the mains heating is literally unable to come on outside of peak times. From 5am to 1pm it's completely switched off, so no wonder the thermostat has no control over it. (This might be simplistic thinking of my part, but could indicate what you suggested...that the previous owner had it set up this way.)

Anyway, will see what the engineer says in a few days.

Thanks.

 

[Basher]

My electricity bill does say "Standard Economy 10", so that part is at least correct.

Excellent. It is probably the appropriate rate for your heating system - that or Economy 7.
Few electricity companies will supply it now. And apparently you can't have a smart meter on Economy 10 according to this:

A Guide to Economy 10 Tariffs, Suppliers and Meters: Is It The Right for You? | OVO Energy

Economy 10 is a 2-rate energy plan offering lower, off-peak rates for 10 hours each day. Find out if Economy 10 is the right choice for you and to help lower your bills.

www.ovoenergy.com

it occurs to me that the mains heating is literally unable to come on outside of peak times. From 5am to 1pm it's completely switched off, so no wonder the thermostat has no control over it. (This might be simplistic thinking of my part, but could indicate what you suggested...that the previous owner had it set up this way.)

Not simplistic thinking at all. You've confirmed that the radiator 'boiler' runs on the off-peak supply only.
So currently you can't have radiators running outside the off-peak hours. Maybe that isn't a problem for you?
It will certainly save money on heating if you stick to your off-peak, but there's that lack of flexibility that comes with it.

Your boiler doesn't care what supply the instantaneous heater is connected to, so there might be other options to run it from an Economy 7 supply (one where the whole house switches from standard rate to off-peak) , but that would involve getting the meter changed and alterations to the wiring, and some expense! But worth investigating if you can't live with the present arrangement, and want the option to have radiators heated a little during the day (it would likely come at a higher cost).

 

[Deena Flannigan]

Hello could someone help please.
I have a heatrae sadistic electromax which should be on ecomany 10 but EDF state I'm on the most expensive tariff.
I use the danfoss thermostat manually but the biggest issue is not having hot water in the morning, any advice please

 

[Basher]

Your Hetarae Sadia Electromax would presumably originally have been installed to run from Economy 10.
So I guess the supply has since changed to a different rate. I'm pretty sure Economy 10 is incompatible with smart meters, so the fitting of a smart meter may have resulted in removing E10?

The Electromax is not particularly suited to any other electricity tariffs. The unit seems to have been designed for when some off-peak electricity was available during the day. Unless already on that rate, I don't think it is available in the market today. You might try asking EDF what they can do for you, or Googling their competitors!

As you may know, the 'boiler' part of the Electromax is an instantaneous water heater, so if you moved to Economy 7, it will only heat the radiators from midnight to 7am at cheap rate, and the rest of the time at peak rate (which on E7 is even more than you are probably paying at the moment, but worth investigating)

As regards hot water, the Electromax cylinder is designed to be heated by off-peak (whenever available), the hot water stored in the tank, and used during the day. If you haven't got hot water in the morning, it sounds as if the immersion heater is not being switched on a couple of hours before you need it. Do you know what is controlling the hot water timing, if anything? I don't believe the thermostat incorporates hot water controls. Do you have a separate switch for hot water somewhere, other than inside the Electromax?

If you haven't got any hot water at all, it's either because 'off-peak' has been disconnected from the unit (hopefully not!), it's because it's not switched on in the Electromax, or the power to it is off or tripped, or the immersion heater is not working. The latter because the over temperature cutout has tripped, or the element gone.

I assume you have the Electromax guide, but it is fairly impenetrable:
https://www.heatraesadia.com/-/medi...ature/user-manuals/electromax_user-manual.pdf

https://www.wolseley.co.uk/wcsstore7.00.805.913/ExtendedSitesCatalogAssetStore/images/products/AssetPush/DTP_AssetPushHighRes/std.lang.all/ti/on/Danfoss_TPOneB_Installation.pdf