Devi Matt running costs CRAZY!

ellmo

Recently moved into house that has a Devi Matt system with a Devireg 550 control set @ 4.5 permanently heating the floor of approx 20sq.mtrs. tiled bathroom. Our Electric bills have been enormous & after investigation have realised the matt is using approx 13 units per day on our metre, this is equal to the cost of everything else we use in the household? Hence our huge bills, basically our electricity costs have doubled. Surely this cannot be right, does anyone have any ideas on this or know anything about this system, cos we just cant afford to leave this turned on if this is normal. Any suggestions greatly appreciated.

Wearb

Approx €2.50 per day to heat 20 metres................. there might be nothing wrong with it. Electricity is an expensive way to heat.

ellmo

Wearb, thanks for reply..... but I just cant believe the system is costing as much to run as it cost us to run the rest of the house!
The system being set @4.5 is the lowest possible setting we can have it at and it only keeps the chill out of the bathroom, you would not feel any heat in the floor. We tried setting it, that it only came on twice a day to heat the bathroom for the time we would be having showers etc but that didn't seem to make any difference to cost maybe it was even worse that way!

Anyway, I think we are going to have to look at some other options to heat the bathroom as we cant afford to keep this running and I am really going mad as the system is good if you could afford it.

Does any know of any other options to run the Devi Matt system, i.e. SOLAR/WIND/BATTERY etc....

antoinolachtnai

It is a big space and if the building is not well constructed, heating it will not be cheap.

What temperature is it maintaining in the bathroom?

A system like that draws a maximum of .2 kW /m2. 20 m makes for 4 kW. If it were on continuously it would be 96 kWh / day. If you are drawing 13 kWh per day then it is on about 12 percent of time.

Easiest thing is to just set it to be on less of the day and run at a lower setting. If there is no lower setting your controller you might have a problem. Running the thing at a lower setting is going to reduce comfort.

The next fastest cheapest fix might be to get a day night meter and get the timer set up so it only comes on at night. This is not really a great option.

A blow heater in the bathroom would heat the space quickly when you need it. You need to get an electrician to fit this. It might be a cheaper and more controllable option though one heater might not be much use in such a big bathroom.

Next easiest is to put a radiator in, and link to central heating.



Best and most expensive solution would really to sort out whatever makes the bathroom so cold.

Effects

Does it have a timer? Set it for the morning and then evening time and avoid heating it when you don't need to.

Tom44

OFF.
Is the most efficient setting.

Bonzo Delaney

I was always under the impression that they were never ment to be used to heat the room. They were just ment to take the cold sting out if the tiles when in your bare feet
Also is there any way you could investigate if there was an insulation layer put under it first. It'd be like a layer 4-12 mm of insulation sandwiched between two cement based sheets. Maybe under the bath you might find evidence of this. Otherwise your just heating the subfloor.

gctest50

Wearb wrote: »

Approx €2.50 per day to heat 20 metres................. there might be nothing wrong with it. Electricity is an expensive way to heat.

depends though

Wearb

gctest50 wrote: »

depends though

From those calculations, electricity costs only improve when on night saver. I would suggest that night saver brings it's own inefficiencies i.e. energy being consumed when there isn't a demand for it. I am referring to the OP's predicament.

gctest50

Wearb wrote: »

From those calculations, electricity costs only improve when on night saver. I would suggest that night saver brings it's own inefficiencies i.e. energy being consumed when there isn't a demand for it. I am referring to the OP's predicament.

for sure, what would be nice here is something like

"Economy 10"

"Economy 10"

...Customers in central Scotland (within the Scottish Power Energy Networks DNO area) have off-peak :

• 3 hours in the afternoon (1.30pm - 4.30pm)
• 4 hours in the evening (8.30pm - 12.30am)
• 3 hours in early morning (4.30am - 7.30am)

Bonzo Delaney

gctest50 wrote: »

for sure, what would be nice here is something like

"Economy 10"

That would never work here for the simple reason it makes far to much sense

ellmo

Hi All, thanks for the feedback. We have tried just heating @ the times we think we rally need it, i.e. morning & evening but this seemed to cost as much as having it at same temp. constant. Assume this is because, the tiles get so cold with no heating on and then it takes probably extra time/heat to get it to the requested temp. in a short period of time. BTW, we also have 2 heated towel rails in the bathroom which come on when the house central heating is on, 1 full sized, floor to ceiling and the one is other half size.

Its not an option to turn down the temperature to lower, as we already have reduced it to a level where we feel it is just about bearable, the temperature is probably about 17/18ish but feels like 14 as its all tiled. It is not a comfortable heat, just enough to kill the frosty chill.

In our last house we had a night meter, which is sort of benificial when we had the kids etc. but now there is only the 2 of us so don't really know if its worth getting the night metre as we mostly only use it for this heating thing & I know the unit cost is a lot cheaper, its half the price, but I think we also had to pay for an extra metre or else our service charge was doubled or something like that, so your costs aren't really half the price.

I don't think I can see the way it was installed, everywhere is tiled including the bath surround, which is inset into a window space and has tiled steps (which are heated, I think) coming down from it to the floor.

At present, looks like best options might be to install either a radiator linked to central heating or else the blow heater, but this would need to be on a timer somehow to account for the heating bathroom for morning time etc.

Bonzo Delaney

ellmo wrote: »

Hi All, thanks for the feedback. We have tried just heating @ the times we think we rally need it, i.e. morning & evening but this seemed to cost as much as having it at same temp. constant. Assume this is because, the tiles get so cold with no heating on and then it takes probably extra time/heat to get it to the requested temp. in a short period of time. BTW, we also have 2 heated towel rails in the bathroom which come on when the house central heating is on, 1 full sized, floor to ceiling and the one is other half size.

Its not an option to turn down the temperature to lower, as we already have reduced it to a level where we feel it is just about bearable, the temperature is probably about 17/18ish but feels like 14 as its all tiled. It is not a comfortable heat, just enough to kill the frosty chill.

In our last house we had a night meter, which is sort of benificial when we had the kids etc. but now there is only the 2 of us so don't really know if its worth getting the night metre as we mostly only use it for this heating thing & I know the unit cost is a lot cheaper, its half the price, but I think we also had to pay for an extra metre or else our service charge was doubled or something like that, so your costs aren't really half the price.

I don't think I can see the way it was installed, everywhere is tiled including the bath surround, which is inset into a window space and has tiled steps (which are heated, I think) coming down from it to the floor.

At present, looks like best options might be to install either a radiator linked to central heating or else the blow heater, but this would need to be on a timer somehow to account for the heating bathroom for morning time etc.

Maybe post up the exact dimensions of the room size of windows whether they're north or South facing and the size of them when the house was built.
Also what the construction of the walls including insulation and floors/ ceilings are
One of the more qualified folk here will be able to work out the btu's needed for the room
Quiet possibly the two towel rads are completely undersized ( give the sizes of these also ) forget about the Devi Mat to heat the space of 20m2
If the wall space allows put in a properly sized rad for the room instead of the towel rail
Insulation and also some level of air tightness or lack of probably plays a massive factor in this also