Electric heating: Boiler + Immersion Heater

rafaetha · 04-09-2014 11:19am #1

Hi everyone.

I've just moved with my wife and kid to an apartment which has electric water heating and electric radiators. I know everyone will comment this will be very costly to run, but there is no gas supply and oil is not an option as it is a block of apartments. I'd really like run everything on the lowest possible cost (hot water and decent heating when the winter comes).

Well, I am struggling to understand how the whole heating system works (previously had gas supply for heating) and I was hoping to get help from someone here. I've asked the landlord and she doesn't have a clue how it works. Here is what I have:

- 1 switch labeled "Boiler" - Amptec Boiler C900 from Heatrae Sadia (product code 95 022 003), 7.5KW - 9kW.
- 1 switch labeled "Immersion" - Thermco Immersion Heater 2.75kW - 3.0kW.
- Solo 03 radiators throughout the house. From what I read they heat up using hot water.
- 1 room thermostat dial

If I turn the Immersion on, I have hot water after about 2.5 - 3 hours, assuming the water was tepid when the heating started. However, no hot water flows to the radiators even when the room thermostat is up.

If I turn the Immersion and the Boiler on at the same time, water gets hot in about 30-40 min, but I understand this will be very costly to run (consuming 3+9 kW). By doing this, however, hot water flows to the radiators.

Can anyone enlighten me about the following:

1- What is the point of having two water heating systems in the same place?

2- How do these boilers work? When the winter comes I want to be able to use the radiators without incurring in massive costs. Will I have to keep the boiler on all the time?

3- By leaving the boiler constantly on, will it consume its toll of 9kW regardless of the water temperature or will it turn on and off automatically when the water temperature drops too much?

4- When the boiler is on, should I keep the immersion on at the same time?

Assuming that the boiler has a smart system, my plan was to heat up the water using the immersion heater, then when the water is fully hot, I'd turn the boiler on (as it seems to be the only thing that triggers the water to be pumped to the radiators) and hope it will only consume electricity if the water temperature drops. Does it make sense? With that in mind...

5 - Should I lower the boiler temp setting to the minimum?

It's a lot of questions, I know... I really hope someone here will be able to shed a light as I have no clue about heating!
Thanks in advance!

antoinolachtnai · 04-09-2014 8:09pm

All the below is based on what you have said. Obviously I have no idea how the whole thing is set up or how big your apartment is, or how well insulated, etc.

1. So that you can heat water without having to heat the radiators? There are better ways of doing this, but this is the way it has been done.

2. I don't know much about them. But really, it's just an electric water heater instead of a gas water heater like was in your last house.

3. I would think it will turn on or off automatically when the temperature reaches the temperature of the water sensor.

4. Is up to you. Won't make much difference to the cost of heating a tank of water. However, if you only want hot water makes more sense to only use the immersion I suppose.

5. This might be a good idea. However if you do this, you will need to leave the boiler switched on for a longer period to heat up the apartment or keep it warm, so you don't necessarily save very much (though you might save a bit by avoiding overheating the apartment). It really depends whether this suits your lifestyle.

Do you have nightsaver electricity? You can check this by looking at the bill, or looking at the meter. You could use this to heat the water and this would reduce the bill, a bit.

I would be inclined to heat the place with electric blow heaters to be honest. Efficiency will be exactly the same and you might get a bit more control.

rafaetha · 04-09-2014 10:37pm

Thank you for taking the time to reply, antoinolachtnai.

I ran a test today, went over to the meter and had dw near the switches. We had the water heating up through the immersion heater for about 2 hours prior to this. When she turned on the boiler switch, I couldn't see any extra electricity consumption reflected on the meter. However, when she turned the wall thermostat dial up, the meter dial started spinning like crazy. I assume that the boiler kicked in with its massive 9kWh consumption. Then the radiators started getting warm. By turning the thermostat dial down, the boiler apparently went back to standby mode.

Well this is confusing. I thought the purpose of the boiler was to heat up water very fast. But with the water already hot, why is it consuming 9kWh just to pump water to the radiators? Isn't that the job of a water pump? Well, at least it automatically turns off based on the wall thermostat dial. I'd really like to find out the best way to use this system. I don't get why the boiler has to kick in when the water is already hot.

antoinolachtnai wrote: »

5. This might be a good idea. However if you do this, you will need to leave the boiler switched on for a longer period to heat up the apartment or keep it warm, so you don't necessarily save very much (though you might save a bit by avoiding overheating the apartment). It really depends whether this suits your lifestyle.

Well, the boiler should turn itself on and off again depending on the temperature setting on the dial. I still need to try reducing the boiler's temperature setting.

antoinolachtnai wrote: »

Do you have nightsaver electricity? You can check this by looking at the bill, or looking at the meter. You could use this to heat the water and this would reduce the bill, a bit.

I don't have night rates and I'm not sure they suit the family needs. Specially because there is no water timer to program it to turn on and off automatically during night rate hours.

antoinolachtnai · 04-09-2014 11:05pm

The boiler heats the water in the radiator circuit. This is a separate, sealed circuit and never mixes with the water in the hot tank that is piped to your taps.

The boiler heats the hot water 'indirectly'. This means that there is a coil (which is just a special type of radiator) inside the hot water tank and this coil is connected to the central heating circuit. This is why the water gets hot when you turn on the boiler.

This is the same, whether you have a gas, electric or oil boiler. The exception is if you have a 'combi' boiler but I don't think that applies in this case.

The purpose of a central heating boiler is to heat the water and then keep it warm. Keeping it warm requires electricity obviously. The water loses heat as it travels through the radiators.

You are referring to a boiler thermostat. Do you actually mean the thermostat on the wall? This is a room thermostat. It measures and is governed by air temperature. A boiler thermostat is attached to the boiler and measures and is governed by water temperature.

rafaetha · 05-09-2014 10:54am

Thanks for making things clearer for me now. So in this case, on the winter months it might be better to use the boiler to heat the coil, which will feed the radiator circuit and also heat up the water for taps and showers. Correct?

I am thinking it might be a good idea to switch to electricity night rates and leave the boiler on all night long during the winter, so that it can heat up the radiators depending on the room thermostat setting. Do you think that with this setting it could be worth changing over?

Thanks again.

antoinolachtnai · 05-09-2014 11:01am

On your first question - it will really make very little difference in terms of price -.

I don't think there is much point having the boiler on at night. The heat will dissipate quickly in the morning. It might make sense if your household gets up very early in the morning and likes the warmth, and if the house is occupied all day. Radiators won't store any heat, and unless your building is very solid and well insulated (which I doubt considering the clods that refurbished it last or built it were stupid enough to put in an electric boiler) it won't store much heat either.

If you can read the meter morning and evening you might be able to figure out if having a night saver meter would be worthwhile. Bear in mind, it costs money to get one taken out.

gctest50 · 05-09-2014 11:18am

Those electric boilers make a bit of sense in the UK , they have " Economy 10 "

you get ~half-price electricity at these sort of times :

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)

rafaetha · 05-09-2014 11:40am

antoinolachtnai wrote: »

I don't think there is much point having the boiler on at night. The heat will dissipate quickly in the morning. It might make sense if your household gets up very early in the morning and likes the warmth, and if the house is occupied all day.

Well, I get up at 6:15 in the morning, still within the night rate. And the house is occupied all day long by kid and wife, who likes the warmth a lot!

antoinolachtnai wrote: »

Radiators won't store any heat, and unless your building is very solid and well insulated (which I doubt considering the clods that refurbished it last or built it were stupid enough to put in an electric boiler) it won't store much heat either.

The apartment block seems well insulated, it is a sunny south facing window and window frames seem to be good (they're danish or something).

antoinolachtnai wrote: »

If you can read the meter morning and evening you might be able to figure out if having a night saver meter would be worthwhile. Bear in mind, it costs money to get one taken out.

That is what I will do, read them before going to bed and then again in the AM. About the meter, I remember reading something about no charges on the first-time switch from 24h to night meter, but this information was contradicted by the guys at Airtricity and Energia too.

rafaetha · 05-09-2014 11:42am

gctest50 wrote: »

Those electric boilers make a bit of sense in the UK , they have " Economy 10 "

you get ~half-price electricity at these sort of times :

That would be amazing! These are off-peak times? Wow. I'd love to get reduced rates on such times!

Leo na · 19-01-2017 12:01pm

Anybody know which company in Dublin can help to repair this electric boiler, ours gave up heating the water this morning...

Searched a lot of boiler companies, seems that they only do gas/oil.

Many thanks

antoinolachtnai · 19-01-2017 2:22pm

This crowd? Just saw on google, don't know anything about them. http://www.dewargasservice.ie/electric-boilers-central-heating-system.html

Leo na · 19-01-2017 2:33pm

Thanks for the infor, they cannot do it though.

antoinolachtnai · 19-01-2017 4:28pm

Surely they must know someone?

It is only an electric boiler, it is pretty simple, someone should be able to fix it. It might be worth trying someone who fixes electric showers.

Does the boiler start at all?

Leo na · 19-01-2017 4:36pm

I finally get in touch with Baxi, who is the distributor of Amptec, they recommended me Brian, here is his contact: 0874040383, in case somebody needs it in the future.

The boiler starts, but doesn't heat up the water, also the red alarm light is flashing. Hope it is not something very serious...

Electric heating: Boiler + Immersion Heater

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