Need new boiler - options confusing 31 January at 5:18PM in Energy 21 replies 730 views

sammyjammy

My boiler is 23 years old and its extremely inefficient.  My home is three beds over three floors 124 year old Victorian mid terrace (but on a hill so the house to left of mine is one story higher which matches my ground floor with their cellar/foundations).  The attic bedroom/roof is adequately insulated, I have double glazing and the ceiling of the cellar (below sitting room) is well insulated.  I have no idea of the EPC but suspect its at least an E.  Without spending £10k plus I don't think there is much more  I can do with it.

Currently I am not using the heating at all, if I put it on for an hour it costs £2 and the only room that gets warm is the sitting room, the rest of the house remains like a freezer (not helped by open doors for three cats.  The kitchen has a concrete floor and its like ice, the radiator is too small so needs replacing,  I think a radiator on the landing may help too.

Anyone thats the background but i am confused. I know the government want gas boilers phased out but they don't seem to be providing a suitable alternative for a house like mine with my budget.  As i see it the only people that will be taking advantage of the £5k heat pump grant are those that could afford to install this in the first place.

I'm guessing I have no choice but just to replace the boiler like for like but grateful for any help/suggestions.

lohr500

I would stick with gas for now, but find a good installer who can look at your existing radiator sizes and advise which would need replacing with larger ones.

Having looked into heat pumps a couple of years ago, I remain to be convinced on the cost effectiveness when retro fitting into older properties.

Compared to replacing like with like (gas or oil boiler) , the extra costs of the main ASHP unit, heat store and radiator changes to support lower running temperatures seem to be way more, even allowing for the £5k grant.

And on running costs, assuming you can get an efficiency of 3 x input energy from the ASHP in the depths of winter, then electricity would need to be no more than +/- 3 times the cost of gas per kWh. On the current deemed tariff in my region (Yorkshire) this isn't the case and gas is still less than 1/3 price of electricity. I also doubt that a heat pump will provide a 3x gain in efficiency when it is really cold outside and you most need the central heating in an old property.

Others may think differently.
  

macman

if you only put it on for an hour then of course it's going to cost you £2 or more, because it will be running flat out to try and get the structure up to the set temp, which it won't do in an hour from a cold start. And a boiler of that vintage won't modulate once it does, it will simply run on/off/on/off continuously.
A modern condensing boiler (yours will almost certainly be non-condensing) with a decent programmer and weather compensation will burn probably burn 20 to 30% less gas for the same kWh output, and modulate down to as little as 10%.
It doesn't have to be like for like, you can have a combi or a conventional boiler depending on your hot water requirements.
Changing or resizing a couple of rads is a trivial task if done at the same time as the boiler change.

sammyjammy

macman said:

if you only put it on for an hour then of course it's going to cost you £2 or more, because it will be running flat out to try and get the structure up to the set temp, which it won't do in an hour from a cold start. And a boiler of that vintage won't modulate once it does, it will simply run on/off/on/off continuously.

That makes alot of sense, I have only recently come off a fixed tariff and to be honest after 1 hour and that cost I panicked and it hasn't been turned on since.

macman

£2 an hour means that it is running at about 20kw's. About the maximum you can expect in CH mode if no modulation, depending on boiler rating.

FreeBear

sammyjammy said: I'm guessing I have no choice but just to replace the boiler like for like but grateful for any help/suggestions.

I'd suggest measuring the sizes of the rooms and windows. Then sit down and punch the numbers in to an online (e.g. https://starsapp.co.uk/basic-heat-loss-calculator/ ). Make a note of the recommended sizes and compare with what you currently have. Chances are, a few of them will be undersized, so budget to replace a few of them - If you specify new radiators throughout, it is worth making the 25-50% bigger. This will allow you to run a gas boiler at a lower return temperature and make full use of the efficiency that comes with it and the rooms will still heat up. Increasing the radiator sizes also means you will be better placed to install a heat pump if/when the time comes.

Disclaimer - I'm looking at replacing a 25+ year old back boiler myself. Gone through the radiator sizing calculations and will be replacing a few of them. Also going to replumb the system to reduce the amount of pipework and route some of it to a point where a heat pump might be connected (using 22mm copper pipe for much of it). Also insulating where I can to reduce the heat losses and plugging all those nasty cold draughts.

Dolor

sammyjammy said:

My boiler is 23 years old and its extremely inefficient.  My home is three beds over three floors 124 year old Victorian mid terrace (but on a hill so the house to left of mine is one story higher which matches my ground floor with their cellar/foundations).  The attic bedroom/roof is adequately insulated, I have double glazing and the ceiling of the cellar (below sitting room) is well insulated.  I have no idea of the EPC but suspect its at least an E.  Without spending £10k plus I don't think there is much more  I can do with it.

Currently I am not using the heating at all, if I put it on for an hour it costs £2 and the only room that gets warm is the sitting room, the rest of the house remains like a freezer (not helped by open doors for three cats.  The kitchen has a concrete floor and its like ice, the radiator is too small so needs replacing,  I think a radiator on the landing may help too.

Anyone thats the background but i am confused. I know the government want gas boilers phased out but they don't seem to be providing a suitable alternative for a house like mine with my budget.  As i see it the only people that will be taking advantage of the £5k heat pump grant are those that could afford to install this in the first place.

I'm guessing I have no choice but just to replace the boiler like for like but grateful for any help/suggestions.

Your boiler is unlikely to be ‘extremely inefficient’ and if it is still working you need to balance the cost of a replacement against higher running costs. Even a modern condensing boiler would struggle to heat the property that you have described. You should be able to check your EPC here:

https://www.gov.uk/find-energy-certificate

That said, you cannot just plumb a new boiler onto an existing heating system without giving the matter a lot of thought. Today’s gas boilers run at a lower flow temperature and efficiency only starts increasing when the returning water flow temperature drops below 56C, so you may need to change the size of some of your radiators to get the required amount of heat into each room.

A 23 year old heating system is also likely to be full of rust and sludge. This needs to be power-washed out of each radiator. This process adds significantly to the cost of the installation. Ignore it at your peril. If a new boiler stops working because of a blocked heat exchanger, it is not covered by the boiler warranty.

Heating is just basic physics. If you set a 20C temperature throughout your home, the heat required to maintain this temperature equals the heat loss. If your property EPC is actually ‘E’ then your priorities should be more insulation and draught exclusion.

Please don’t take this as a criticism. The reason why you are using £2 of gas in the first hour is because the structure of your home is cold. As room temperatures increase, boiler output reduces (as does gas kWh input) as the graph below shows:



That said, if you are not turning your boiler on, why are you thinking of a bigger radiator in your kitchen? It will just increase your energy usage? In sum, you need to go back to basics and seek professional advice if necessary from someone who is not trying to sell you something.

Lorian

Is it possible to fit catflaps?

FreeBear

Dolor said: Please don’t take this as a criticism. The reason why you are using £2 of gas in the first hour is because the structure of your home is cold. As room temperatures increase, boiler output reduces (as does gas kWh input) as the graph below shows:

If the OPs boiler is capable of modulating down, then I would agree, gas consumption will drop as the property heats up. But at 23 years old, it probably doesn't have the ability. So at best, the boiler will cycle on & off one the place gets up to temperature.

sammyjammy

Lorian said:

Is it possible to fit catflaps?

Possible yes, desirable no, maybe should get rid of the cats!

sammyjammy

Dolor said:

sammyjammy said:

My boiler is 23 years old and its extremely inefficient.  My home is three beds over three floors 124 year old Victorian mid terrace (but on a hill so the house to left of mine is one story higher which matches my ground floor with their cellar/foundations).  The attic bedroom/roof is adequately insulated, I have double glazing and the ceiling of the cellar (below sitting room) is well insulated.  I have no idea of the EPC but suspect its at least an E.  Without spending £10k plus I don't think there is much more  I can do with it.

Currently I am not using the heating at all, if I put it on for an hour it costs £2 and the only room that gets warm is the sitting room, the rest of the house remains like a freezer (not helped by open doors for three cats.  The kitchen has a concrete floor and its like ice, the radiator is too small so needs replacing,  I think a radiator on the landing may help too.

Anyone thats the background but i am confused. I know the government want gas boilers phased out but they don't seem to be providing a suitable alternative for a house like mine with my budget.  As i see it the only people that will be taking advantage of the £5k heat pump grant are those that could afford to install this in the first place.

I'm guessing I have no choice but just to replace the boiler like for like but grateful for any help/suggestions.

Your boiler is unlikely to be ‘extremely inefficient’ and if it is still working you need to balance the cost of a replacement against higher running costs. Even a modern condensing boiler would struggle to heat the property that you have described. You should be able to check your EPC here:

https://www.gov.uk/find-energy-certificate

That said, you cannot just plumb a new boiler onto an existing heating system without giving the matter a lot of thought. Today’s gas boilers run at a lower flow temperature and efficiency only starts increasing when the returning water flow temperature drops below 56C, so you may need to change the size of some of your radiators to get the required amount of heat into each room.

A 23 year old heating system is also likely to be full of rust and sludge. This needs to be power-washed out of each radiator. This process adds significantly to the cost of the installation. Ignore it at your peril. If a new boiler stops working because of a blocked heat exchanger, it is not covered by the boiler warranty.

Heating is just basic physics. If you set a 20C temperature throughout your home, the heat required to maintain this temperature equals the heat loss. If your property EPC is actually ‘E’ then your priorities should be more insulation and draught exclusion.

Please don’t take this as a criticism. The reason why you are using £2 of gas in the first hour is because the structure of your home is cold. As room temperatures increase, boiler output reduces (as does gas kWh input) as the graph below shows:



That said, if you are not turning your boiler on, why are you thinking of a bigger radiator in your kitchen? It will just increase your energy usage? In sum, you need to go back to basics and seek professional advice if necessary from someone who is not trying to sell you something.

No offence taken, every day is a school day bigger radiator in the kitchen is in hope that energy costs one day go back to a near normal one day.  It does make sense that the longer its on the less per hour it will cost in theory but the costs of that are just too great for me right now to be able to do it, not sure off and on again would be much more helpful either as it gets so cold so quickly.

Fingers crossed spring and some milder weather comes quickly.

When I came home from work earlier the temp gauge in car said 12c, it was 13.5c in the house!