My first electricity bill...

[bigreadie]

..is £820 for the quarter.  I appreciate it is winter and the pump works harder but I wasn't expecting that.

 

Lighting wise I have the open fitted with spots (only since Dec) and appliance wise (again since Dec) couple of ovens, hob, 2x F/F and a dishwasher which leads me to think the UFH is the culprit.

 

I have looked at the UFH pump (a wilo 25/6) and found that the setting on this was not correct for the UFH so have change the profile as per the manual but couldn't work out what speed to set so went for the medium. I only have 5 zones from the 10 zone manifold active ( four controlled by a neostat) and one zone (bedroom)that is on but with the little TRV so comes on and off with the open plan.

 area.  Flow rates are set to 1.5ish l/m.  I have a 40l buffer but have found that when the heating comes on this drains and before the required room temp is reached it empties and I am pumping cold water around the system.  None of the floors are warm (which the wife is most annoyed by) although the house does not feel cold.

 

The UFH pipes etc was installed by the screed company and the water works and pump by a reputable plumbers.  I connected the flow and return to the cylinder and when the commissioned that they said there was no issues with the plumbing between the two.  I would have called someone out to have a look but I am skint now...any ideas please?

 

thanks in advance  

 

 

[AliG]

The max power consumption of your UFH pump appears to be 99W so it cannot be driving up your bill.

 

https://wilo.com/in/en/Products-and-expertise/Series-Finder/Star-RS-25-6_1931.html

 

A few simple questions before we start-

 

1. I assume the bill is based on meter readings and not an estimate?

2. Do you have a gas boiler or ASHP?

3. Is the immersion on?

4. What rate per kWh are you on?

 

I have a swimming pool and a Tesla and don't use that much electricity so something seems odd.

[bigreadie]

2 minutes ago, AliG said:

The max power consumption of your UFH pump appears to be 99W so it cannot be driving up your bill.

 

https://wilo.com/in/en/Products-and-expertise/Series-Finder/Star-RS-25-6_1931.html

 

A few simple questions before we start-

 

1. I assume the bill is based on meter readings and not an estimate?

2. Do you have a gas boiler or ASHP?

3. Is the immersion on?

4. What rate per kWh are you on?

 

I have a swimming pool and a Tesla and don't use that much electricity so something seems odd.

Hi AliG.

 

Thanks for the reply - much appreciated.

 

Q1.  meter reading

Q2.  ASHP Nibe 2040

Q3. Fires once every 2 weeks to take the temp about 55 degs

Q4. 16.68p

 

I'm worried as a) its excessive, b) i haven't got all the electrics second fixed yet (including MVHR), and c) like I said half the house isn't even heated!

 

rgds

[PeterW]

How big is the house and how big is the ASHP ..?

[bigreadie]

1 minute ago, PeterW said:

How big is the house and how big is the ASHP ..?

140ish sqm, bungalow, ICF and warm roof.   The heat pump is Nibe F2040 8kW

[AliG]

@bigreadie can you have a look at this thread where we went through a lot of the issues that might be causing high bills on an ASHP, a very similar situation to yours.

 

https://forum.buildhub.org.uk/topic/18532-meter-readings-panic-and-electricity-costs/

 

In this situation the ASHP had its own usage display on their Consumer unit and on the ASHP, do you have this? It is almost certain that your ASHP is the culprit. It will use a lot of electricity when it is cold though TBF.

 

One easy thing though is to change your electricity supplier. You should be able to get it for less than 15p/kWh so that would help a bit.

 

If you look at the other thread you might expect, very roughly, to use 30kWh a day for heating, 10kWh a day for hot water and 10kWh for general electricity use during the coldest part of winter. That is not far off where you are. The heating would fall considerably in spring and autumn.

 

Edited January 27, 2021 by AliG

[bigreadie]

23 minutes ago, AliG said:

@bigreadie can you have a look at this thread where we went through a lot of the issues that might be causing high bills on an ASHP, a very similar situation to yours.

 

https://forum.buildhub.org.uk/topic/18532-meter-readings-panic-and-electricity-costs/

 

In this situation the ASHP had its own usage display on their Consumer unit and on the ASHP, do you have this? It is almost certain that your ASHP is the culprit. It will use a lot of electricity when it is cold though TBF.

 

One easy thing though is to change your electricity supplier. You should be able to get it for less than 15p/kWh so that would help a bit.

 

If you look at the other thread you might expect, very roughly, to use 30kWh a day for heating, 10kWh a day for hot water and 10kWh for general electricity use during the coldest part of winter. That is not far off where you are. The heating would fall considerably in spring and autumn.

 

There's alot on that tread!...I'll go through and see if it helps.

 

another couple of question though...is it normal that the buffer runs out before reaching the correct temp?  would switching to heating on all day be more efficient (so there is not so much of a draw when the thermostat signals)?

[PeterW]

Just now, bigreadie said:

another couple of question though...is it normal that the buffer runs out before reaching the correct temp?  would switching to heating on all day be more efficient (so there is not so much of a draw when the thermostat signals)?

Yes - it’s just there to stop the floor short cycling the heat pump. Where is the stat that controls the heat pump..?

 

What you should find is the buffer empties and the heat pump kicks in and then the water is going direct into the floor. Have you got thermometers on the flow and return from the manifold ..?

 

How often is the heat pump running ..?? 

[AliG]

I don't know about the buffer, I will let an ASHP expert answer that. I think it is what should happen though as the ASHP heats the buffer to stop it short cycling.

 

In my experiments leaving the heating on all the time versus switching off and on has had similar cost. I would imagine in your house which I think is ICF you would have quite low losses and would be as well leaving it on all the time (which could allow you to use cheaper off peak electricity). Until you know if and why it is using more electricity than expected  would hold off though,

 

For an ASHP running a lower flow temperature for a longer period of time should be cheaper as it improves the COP. Do you know your flow temp?

Edited January 27, 2021 by AliG

[nod]

1 hour ago, bigreadie said:

..is £820 for the quarter.  I appreciate it is winter and the pump works harder but I wasn't expecting that.

 

Lighting wise I have the open fitted with spots (only since Dec) and appliance wise (again since Dec) couple of ovens, hob, 2x F/F and a dishwasher which leads me to think the UFH is the culprit.

 

I have looked at the UFH pump (a wilo 25/6) and found that the setting on this was not correct for the UFH so have change the profile as per the manual but couldn't work out what speed to set so went for the medium. I only have 5 zones from the 10 zone manifold active ( four controlled by a neostat) and one zone (bedroom)that is on but with the little TRV so comes on and off with the open plan.

 area.  Flow rates are set to 1.5ish l/m.  I have a 40l buffer but have found that when the heating comes on this drains and before the required room temp is reached it empties and I am pumping cold water around the system.  None of the floors are warm (which the wife is most annoyed by) although the house does not feel cold.

 

The UFH pipes etc was installed by the screed company and the water works and pump by a reputable plumbers.  I connected the flow and return to the cylinder and when the commissioned that they said there was no issues with the plumbing between the two.  I would have called someone out to have a look but I am skint now...any ideas please?

 

thanks in advance  

 

 

Now that a lot I may have to rethink the heat pump on our next build 

We are at £240 gas for the last three months and just over £232 electric for the same period 

Our house is 260m2 traditional built 

I thought going to the extra expense of a heat pump would had bills 

Edited January 27, 2021 by nod

[AliG]

1 minute ago, nod said:

I thought going to the extra expense of a heat pump would had bills 

 

Electricity costs around 6x as much as gas per kWh so you cut CO2 emissions but not costs. However, you do get a big payment from the RHI and save on putting in a gas supply.

[ProDave]

I use about £50 of non heating electricity in a month and at this time of year about £100 for heating.

 

So lets just say £700 of your electricity is for heating.  That seems an awful lot for an ICF house about the same size as mine

 

I would start by taking a reading every day at the same time and tabulating it.  If there is no inbuilt metering to say how much the ASHP is using, get an electrician to install it's own electricity meter so you have an independent measure of how much the ASHP is actually using on it's own.

 

Then you can work out what is happening.

[SteamyTea]

1 hour ago, bigreadie said:

The UFH pipes etc was installed by the screed company

Do you know how much insulation is under the pipes?

[joe90]

My floors don’t feel warm either but the house is a steady 21’ give or take 1’. My buffer is 80 litres, my ASHP is on 24/7 controlled by a stat on the buffer tank and has never run out (that I have noticed). My total electricity usage in mid winter is £130 ish.

[ProDave]

Do you have a thermometer on the UFH manifold, that will tell you what the temperature of the UFH water is.

 

Like @joe90 our UFH floors don't feel particularly warm even walking on them in bare feet, more a question of they "don't feel cold"  Typically with the UFH on the floor surface temperature is about 22 degrees.

 

@nod don't panic about cost.  Our 150 square metre TF house built close to passive house levels of insulation costs less than £250 per year for space heating with the ASHP.  And others (probably in a milder climate than the east Highlands) have even lower heating bills.

[nod]

1 hour ago, AliG said:

 

Electricity costs around 6x as much as gas per kWh so you cut CO2 emissions but not costs. However, you do get a big payment from the RHI and save on putting in a gas supply.

RHi ?

Edited January 27, 2021 by nod

[SteamyTea]

As @PeterW pointed out, a buffer tank is not a thermal store, or even a UVC/VC.

It is just there to smooth out the temperature fluctuations while also helping to keep the heat pump working within its optimum range.

Think of it as a capacitor in an electrical circuit, rather than a battery.  The formula for calculation is the same.

[bigreadie]

1 hour ago, ProDave said:

I use about £50 of non heating electricity in a month and at this time of year about £100 for heating.

 

So lets just say £700 of your electricity is for heating.  That seems an awful lot for an ICF house about the same size as mine

 

I would start by taking a reading every day at the same time and tabulating it.  If there is no inbuilt metering to say how much the ASHP is using, get an electrician to install it's own electricity meter so you have an independent measure of how much the ASHP is actually using on it's own.

 

Then you can work out what is happening.

Just started the readings...as the immersion and heat pump have their own meters so will be able to see what the consumption is.  I don't have regular readings but i know that the meters were all at zero when installed so can work out a daily average from that.  I'm also planning changing to an always on programme to see how that compares...surely it won't cost any more!!

Edited January 27, 2021 by bigreadie

[bigreadie]

42 minutes ago, ProDave said:

Do you have a thermometer on the UFH manifold, that will tell you what the temperature of the UFH water is.

 

Like @joe90 our UFH floors don't feel particularly warm even walking on them in bare feet, more a question of they "don't feel cold"  Typically with the UFH on the floor surface temperature is about 22 degrees.

 

@nod don't panic about cost.  Our 150 square metre TF house built close to passive house levels of insulation costs less than £250 per year for space heating with the ASHP.  And others (probably in a milder climate than the east Highlands) have even lower heating bills.

flow into the manifold is 40 deg and that is exactly how the floor feels!

 

[bigreadie]

1 hour ago, SteamyTea said:

Do you know how much insulation is under the pipes?

170mm and 50mm screed floor.  No tiles yet as I haven't got that far

[newhome]

53 minutes ago, nod said:

RHi ?

Renewable Heat Incentive. Basically a bung from the government to encourage people to install renewable heating technology such as an ASHP. It’s stopping next year though so will be too late for your next build. It might be replaced by something else but nothing has been announced yet. 
 

 

[Gone West]

10 hours ago, bigreadie said:

as the immersion and heat pump have their own meters so will be able to see what the consumption is

What's the immersion for. It could well be using a lot of electricity, have you tried turning it off.

[joe90]

10 hours ago, bigreadie said:

flow into the manifold is 40 deg and that is exactly how the floor feels!

Wow, my UFH temp is 25’ my DHW is heated to 48’ and I can hardly hold my hand under the hot tap, 40’ is very hot (IMO).

[ProDave]

10 hours ago, bigreadie said:

flow into the manifold is 40 deg and that is exactly how the floor feels!

 

If the floor surface temperature is anything close to 40 degrees, and the house is well insulated, it would feel like an oven in there.  something is not sounding right.

[joe90]

10 hours ago, bigreadie said:

flow into the manifold is 40 deg and that is exactly how the floor feels!

Q, is that before the blending valve?