09-02-2012, 12:33 PM
Hi Steve,
When our boiler broke, we used our electric immersion heater for about 6-8 weeks. It added around £200 to our electricity bill! Clearly, we weren't paying much for gas during this period, so the gas bill was around £200 less than normal, but that £200 would have heated the whole house as well as the water!
Pretty early on, we realised that we were wasting our money by switching it on and off, so left it on continuously. The heat loss through the well-insulated cylinder is quite low.
We don't have economy 7, and there are four of us here. Between us, each day we have two showers and bath the kids after tea, and the shower is a pumped power shower. I guess you use a lot less water than us...
We had a gas-fired instantaneous hot water heater in our last house, and it wasn't bad. Pretty economical to run, despite having a pilot, but it took a while to fill a hot bath, especially in winter - and that would have been annoying if we'd had the kids back then.
Looking at the link, they look quite good for the money. I'm interested to see that one of them doesn't require electricity (just like our old one), and this has certain advantages - I remember one time when we were without electricity for 3 days, and our house was one of the few on our estate that could have heat, hot water and cook, thanks to our low-tech hot water heater, gas cooker and gas fire. Everyone else had modern boilers and cookers that wouldn't operate in the absence of mains.
They are both quite powerful at ~23kw, so should be good for a shower. Will definitely be cheaper to run than the electric immersion heater - although personally, I like the reassurance that the immersion heater is there to cover boiler breakdowns.
Because these things are simple non-condensing burners, I'd wonder if they are as energy-efficient as a modern condensing boiler? One of them even has a pilot light!
Of course, these will free up the space that your hot water cylinder takes, and you'll be able to remove the cold water tank in the loft if nothing else uses it (though connecting bathroom taps, etc, to the rising main instead should be easy enough - though you might get condensation on the outside of the cistern and perhaps you'll need to change a few washers if they are seeing mains pressure for the first time). But care in siting them is required because of the flue - especially so in the non-fan version. And what are you using for a shower? If it's fed from the existing hot water cylinder, perhaps via a pump, then you might need to change the mixer valve and shower head for one that is suitable for mains pressure (low flow rate, high pressure, as opposed to high flow rate at low pressure).
An outside thought; if you're going to the effort of installing something like this, is it worth considering getting a gas-fired heating system installed? If there's only you, and you're willing to deal with the cold, then it might be tempting to concentrate on just heating the water, but it might be better to think about the bigger picture. Personally, I think that it's a mistake to avoid heating a house that's occupied because the lower temperatures will encourage condensation, damaging the decoration and potentially causing a health risk. I know you have open fires, and these will provide good ventilation that will help with this issue, but open fires have a negative overall efficiency rating when you consider the times they aren't used.
Of course, this is going far beyond your original question, but these things do tend to spiral when you think them through. But most of a CH install can be a DIY job, which is a good way to keep the costs down.
Hope this helps,
Mark
When our boiler broke, we used our electric immersion heater for about 6-8 weeks. It added around £200 to our electricity bill! Clearly, we weren't paying much for gas during this period, so the gas bill was around £200 less than normal, but that £200 would have heated the whole house as well as the water!
Pretty early on, we realised that we were wasting our money by switching it on and off, so left it on continuously. The heat loss through the well-insulated cylinder is quite low.
We don't have economy 7, and there are four of us here. Between us, each day we have two showers and bath the kids after tea, and the shower is a pumped power shower. I guess you use a lot less water than us...
We had a gas-fired instantaneous hot water heater in our last house, and it wasn't bad. Pretty economical to run, despite having a pilot, but it took a while to fill a hot bath, especially in winter - and that would have been annoying if we'd had the kids back then.
Looking at the link, they look quite good for the money. I'm interested to see that one of them doesn't require electricity (just like our old one), and this has certain advantages - I remember one time when we were without electricity for 3 days, and our house was one of the few on our estate that could have heat, hot water and cook, thanks to our low-tech hot water heater, gas cooker and gas fire. Everyone else had modern boilers and cookers that wouldn't operate in the absence of mains.
They are both quite powerful at ~23kw, so should be good for a shower. Will definitely be cheaper to run than the electric immersion heater - although personally, I like the reassurance that the immersion heater is there to cover boiler breakdowns.
Because these things are simple non-condensing burners, I'd wonder if they are as energy-efficient as a modern condensing boiler? One of them even has a pilot light!
Of course, these will free up the space that your hot water cylinder takes, and you'll be able to remove the cold water tank in the loft if nothing else uses it (though connecting bathroom taps, etc, to the rising main instead should be easy enough - though you might get condensation on the outside of the cistern and perhaps you'll need to change a few washers if they are seeing mains pressure for the first time). But care in siting them is required because of the flue - especially so in the non-fan version. And what are you using for a shower? If it's fed from the existing hot water cylinder, perhaps via a pump, then you might need to change the mixer valve and shower head for one that is suitable for mains pressure (low flow rate, high pressure, as opposed to high flow rate at low pressure).
An outside thought; if you're going to the effort of installing something like this, is it worth considering getting a gas-fired heating system installed? If there's only you, and you're willing to deal with the cold, then it might be tempting to concentrate on just heating the water, but it might be better to think about the bigger picture. Personally, I think that it's a mistake to avoid heating a house that's occupied because the lower temperatures will encourage condensation, damaging the decoration and potentially causing a health risk. I know you have open fires, and these will provide good ventilation that will help with this issue, but open fires have a negative overall efficiency rating when you consider the times they aren't used.
Of course, this is going far beyond your original question, but these things do tend to spiral when you think them through. But most of a CH install can be a DIY job, which is a good way to keep the costs down.
Hope this helps,
Mark
