Replacement oil boiler - options?

[elkay]

Hi,

We are currenlty renovating our new property before moving in. It currently has a 23yr old Grant boiler, which we have decided to replace. A boiler engineer has recommended a combi boiler, and getting rid of our hot water tank. However, the quantity surveyor suggested that we should keep the hot water tank, as he says that the combi boiler will not provide enough hot water for a bath.
- I would have thought that quantity of hot water wouldn't be a problem, as it will be heating it on demand, so is the QS mistaken?
- Would the hot water be a powerful enough flow for a shower, or should we get an electric shower?
- Any other disadvantages of going without the hot water tank? The only time we use it in out current house is when filling the bath.
- Any other pros/cons for a combi boiler on it's own?

Also...the current boiler is indoors. Would there be any issues with installing the new boiler outdoors? It would help with utility room space.

TIA
Elkay

[Mike4]

Hi,

We are currenlty renovating our new property before moving in. It currently has a 23yr old Grant boiler, which we have decided to replace. A boiler engineer has recommended a combi boiler, and getting rid of our hot water tank. However, the quantity surveyor suggested that we should keep the hot water tank, as he says that the combi boiler will not provide enough hot water for a bath.
- I would have thought that quantity of hot water wouldn't be a problem, as it will be heating it on demand, so is the QS mistaken?
- Would the hot water be a powerful enough flow for a shower, or should we get an electric shower?
- Any other disadvantages of going without the hot water tank? The only time we use it in out current house is when filling the bath.
- Any other pros/cons for a combi boiler on it's own?

Also...the current boiler is indoors. Would there be any issues with installing the new boiler outdoors? It would help with utility room space.

TIA
Elkay

I live with an oil combi and for bath filling, it's terrible. The hot water flow rate is initially good (as its a storage combi) but after the first 20 litres or so, the temperature tumbles to near-cold unless I turn the tap down to little more than a trickle. So I'd agree with your QS, beware!

It works really well for a shower though as showers don't need the flow rate necessary to fill a bath, and being a bloke I don't spend 20 minutes at a stretch in the shower.

Bottom line is, the hot water flow is proportional to the power rating of the boiler. If you choose a 40 or 50 kW oil combi it might just about fill a bath adequately quickly. Have a careful read of the specs of whatever combi is being recommended to you.

(Heating engineers like proposing combis as they are quicker and MUCH cheaper than a boiler and a hot tank.)

[BullDog]

Well, I admit to being a bit old school here. If you have a hot water cylinder you probably have an immersion heater fitted to it. We rarely use ours, but it's good to know that if the boiler fails over a weekend or a bank holiday, then we can still heat the hot water tank with the immersion heater. On the other hand, if you have a power cut and neither the immersion heater nor the gas boiler are working, then it's probable you still have some hot water available in the tank. If you go to a combi boiler, neither of those options apply. Personally, I say if the hot water tank is well insulated, is fitted with a functioning thermostat and is in good condition, I would not throw it away for a combi boiler. As I said, I am a bit old school. But to me, the advantages of retaining the hot water tank are too much to give up. Finally, we like the airing cupboard where our tank is. Without the hot water tank, we wouldn't have an airing cupboard. Hope that helps.

[Mike4]

P.S.

Oil boilers are often fitted outside as even the slightest oil leak makes the house smell of oil, which smells like diesel. As always there are trade-offs. With an outside boiler it is harder to get it serviced or repaired if the weather is foul. Also, out of sight, out of mind applies and outside boilers tend to get less well looked-after than those inside.

[Dod101]

I wold go for a standard oil fired boiler with a megaflo tank. This is an unvented hot water cylinder enabling you to have hot water literally on tap. It has excellent hot water pressure and you do not need a cold water tank. I think they usually come with an immersion heater built in. The whole thing can of course be combined with central heating.

I suppose you can have an oil fired boiler outside. Mine is in my garage and I have never had any problem with the smell of oil from it. Properly maintained they should not smell.

Dod

[Bminusrob]

I have just had a new Grant oil boiler installed (18 months ago),and I am very impressed. I would recommend, like us, having an unvented (pressurised) hot water cylinder. Recently, I exprimented with using the electric immersion eater instead of the oil heating for hot water, and, even at £1 per llitre, electric heating cost at least double the cost of oil heating.

[elkay]

Thanks for the feedback folks, though it's given me even more food for thought

We rarely use the bath, so may accept the limitation, now that we understand it. The key benefits are on demand hot water, and space savings (particularly where we need it). We currently have regular boiler and hot water tank/immersion heater, and the only time the immersion heater is used is for a bath. But there are a number of lesser considerations, so I'll probably dither a little before I make a decision.

However, it does raise another question, if we go for the combi...we will be creating a shower room as part of the renovations, and I'm wondering if the output from the combi will be at least a match for a standard electric shower, or should we just go for the electic shower option. And I've no idea how powerful either option will be, I assume they both will be affected by the mains water pressure.

regards
elkay

[Dod101]

Thanks for the feedback folks, though it's given me even more food for thought

We rarely use the bath, so may accept the limitation, now that we understand it. The key benefits are on demand hot water, and space savings (particularly where we need it). We currently have regular boiler and hot water tank/immersion heater, and the only time the immersion heater is used is for a bath. But there are a number of lesser considerations, so I'll probably dither a little before I make a decision.

However, it does raise another question, if we go for the combi...we will be creating a shower room as part of the renovations, and I'm wondering if the output from the combi will be at least a match for a standard electric shower, or should we just go for the electic shower option. And I've no idea how powerful either option will be, I assume they both will be affected by the mains water pressure.

regards
elkay

You seem set on a combi. Well, that is up to you but if you take the megaflo option, you have no need to worry about an electric shower. I have both. Part of my house is fed from the megaflo and part from the electric shower/header tank. There is no question about which is better.

You are presumably planning for the long term. Think long term as well.

Dod

[elkay]

bi. Well, that is up to you but if you take the megaflo option, you have no need to worry about an electric shower. I have both. Part of my house is fed from the megaflo and part from the electric shower/header tank. There is no question about which is better.

You are presumably planning for the long term. Think long term as well.

Dod

I haven't ruled it out entirely, and have read a couple of different articles. This one provides a good comparison of the 2 options:
https://www.advancedheatingplumbing.co. ... hats-best/
As there are only 2 of us, and that number will only reduce, our hot water needs are limited to a daily shower each and hand washing. So taking all the factors into consideration, the combo looks like it will meet our needs better. I will be having a chat with the heating engineer, before making a final decision. But thanks for your input - your preference and experience of the mega flow is one of the reasons I'm dithering

Elkay

[AsleepInYorkshire]

Hi,

We are currently renovating our new property before moving in. It currently has a 23yr old Grant boiler, which we have decided to replace. A boiler engineer has recommended a combi boiler, and getting rid of our hot water tank. However, the quantity surveyor suggested that we should keep the hot water tank, as he says that the combi boiler will not provide enough hot water for a bath.
- I would have thought that quantity of hot water wouldn't be a problem, as it will be heating it on demand, so is the QS mistaken?
- Would the hot water be a powerful enough flow for a shower, or should we get an electric shower?
- Any other disadvantages of going without the hot water tank? The only time we use it in out current house is when filling the bath.
- Any other pros/cons for a combi boiler on it's own?

Also...the current boiler is indoors. Would there be any issues with installing the new boiler outdoors? It would help with utility room space.

TIA
Elkay

Firstly may I say QS's are never mistaken

You haven't mentioned if the works you are doing to your new home include improvements to the insulation. This could include increased depths of loft insulation, additional insulation to walls and if possible installation of insulation to ground floors and possibly installing under floor heating. Additionally draft proofing is essential where you home meets the external environment. If you have or are going to such lengths it may be possible to consider an ASHP (air source heat pump) as your heat source. From what I understand ASHP's are ecologically quite friendly and in combination with underfloor heating (UFH) they can be very efficient. ASHP's are powered by electricity. However, unlike gas or oil boilers they are much more efficient at producing heat. They range from 300-400% efficiency. So for every 1kw of electricity that goes into them 3-4kw's worth of heat comes back out. I think gas and oil boilers float around at 80-95% efficiency. ASHP's life spans of 25 years can be achieved. The ASHP is fitted outside. They require a hot water store. They can also be used to cool your home in hot weather, although you would need to install additional equipment inside for this.

You may be nearing completion of your works and the option of installing ASHP may have been missed or simply may not be suitable. As our reliance upon fossil fuels is reduced to meet our carbon footprint targets I think there's the potential for the cost of fossil fuels like oil to rise as demand falls.

Perhaps there are better websites out there. This link will give you a decent overview of ASHP.
https://www.greenmatch.co.uk/blog/2016/ ... heat-pumps

Overall ASHP's should save money when compared to an oil or gas sourced heating system. Recent energy price rises have removed some of that, but ASHP remains as cost effective as gas and oil, with a much lower carbon footprint.

It can't be used in homes with low insulation or where draft proofing is poor. If these are present but the option to install UFH isn't viable then existing radiators would need to be increased in size. The operating temperature of the water in ASHP systems is much lower than gas and oil systems.

As Dod has mentioned Megaflo is worth buying just for the experience of showering. If I recall correctly the term that is used is "power showering". However, if you don't have space to fit it or you have a set budget it may not be a viable option.

I think your QS was right to advise caution relating to combi boilers. They do have their place though and should be part of your considerations as you progress.

AiY(D)
QS

[scotview]

If minimising gas usage or CO2 reduction is important to you, one other consideration is heating controls and boiler sizing.

We have had a zoned heating system for a couple of years which means that we only heat the rooms we use.

Furthermore this has allowed us to install a very small conventional boiler rated at 15kW (BG recommended 25 kW). This has very good turn down efficiency at low flow. The house takes slightly longer to heat up from cold but I'm sure it still has a quicker cold start than a heat pump. Our gas usage has reduced, the heating is more targeted and we are doing our green bit. Combi boilers are very energy wasteful but that maybe isn't important to you.

Our next move will probably be to install a more efficient HW cylinder like a megaflo and remove our CW header tank. Not too sure how these will interface with a boiler with low kW rating but looking into it. For future proofing you maybe want to check that your new boiler can handle a hydrogen mix.

[scrumpyjack]

I have had a Grant oil boiler for years and am very happy with it. I too would go for a hot water tank with backup immersion heater. Whenever I have encountered a system with hot water heated at the point of demand it has never been satisfactory. When we had our plumbing system redone, and went for a pressurised system with no feeder tanks (highly recommend) we put the hot water tank in the garage to save space but kept a smaller airing cupboard. That works well. I also have an AHSP for the swimming pool which the oil boiler can heat as well. I have found the oil boiler far cheaper to run for pool heating than the AHSP.

Ps have a Tado system to control all the radiators which is excellent

[didds]

We have a combi boiler (oil) and have used them for over twenty years. It provides enough water for a bath certainly. FWTW its a worcester (as was its predecessor).

Other than that, my gut feeling (as we followed when we had our initial boiler installed and then replaced 20 years later) was to follow the suggestion of the boiler installer as to make and model, and that would be one he was actually au fait with most. I suppose the alternative would be to identify which boiler best fits your needs (howsoever you achieve that independently), and then find an installer that is au fait with THAT make and model (howsoever one does that).

didds

[88V8]

Would there be any issues with installing the new boiler outdoors? It would help with utility room space.

One disadvantage ... you would lose the emitted heat from the boiler casing, which can be as much as a radiator. The maker's bumph should include that figure.

V8

[Mike4]

We have a combi boiler (oil) and have used them for over twenty years. It provides enough water for a bath certainly. FWTW its a worcester (as was its predecessor).

My oil combi which delivers pathetic performance at filling a bath is also a Worcester....

What actually counts is the heat output into the hot water, rather than the brand.

A 24kW combi will take an age to fill a big roll-top cast iron bath like wot I has in my hovel. A (say) 40kW combi filling (say) a standard-sized acrylic bath with be a different kettle of fish figuratively speaking.

[elkay]

Thanks again for all the feedback. I'm still leaning towards the combi, and possibly go up a step in output (the incremental cost is not much considering the lifespan). Also, our bath is small...

I have considered ASHP, but my brother's experience with heat pumps (his is GSHP) and reliability problems, along with the significant installation cost, and the increased insulation required to make it viable, does not make it a pragmatic solution. I will pay more for greener energy, but I haven't been convinced by the options available to me.

Another significant factor is disruption - my wife is already stressed out by the work planned, and any significant increase to that work would probably push her over the edge...

Thanks all
ELkay