Diesel Heater, emergency use & costs vs gas combi boiler + electric supply for it?

pluto2010

Hi.

I'm really thinking of every option at the minute.

Background: I live in a 1 bed ground floor flat, fairly well insulated, currently havnt had to turn the heating on and temperatures havnt dropped below 19.5c.  No chimney, have a garden.
The combi boiler is rated 5.1 - 25.6kwh. Last year it ran for 5 hours on the coldest days( nest figures so not firing figures).
We seem to get alot of power cuts the other week for 5 hours in the evening,
I have 2 small 1000va/6600watt UPSs which I'm looking to extend with a deepcycle leisure battery for increased run time.

Problem: Apart from gas being blooming expensive, if the electric goes there won't be any heat. 
I'm looking of a way to heat to a acceptable level so I can also provide shelter for elderly neighbours that doesnt have a huge up front cost.


Ideas/thoughts:(Numbers are guess work at the mo)

-Combi boiler per night:
8kwh for 5 hours average : £4 per night

-Diesel heater, I'm looking at a 8kwh diesel heater, this is where I need help. The diesel heater I'm looking at is 8kw heater consuming 0.1-0.24 L/H.
*These require a 12v supply, I'm unable to find much info on how many watts at 240v they use though?  I'm thinking in a emergency plugging into the UPS 3 pin outlet and trying to calculate run time.
8kw @ 0.24L/H, diesel@£1.90L = £2.37 For 5 hours at max 8kw.
*What am I missing, why is it cheaper than gas combi buy a fair bit?
If using the diesel heater in a emergency I would be locking down and only using the the living room 5x3metres so likely will use less diesel.

-Other options?
Are there any other options that are possible that can run with no/very little electric?
I've looking into external rocket stoves heating a coil of water going to a radiator indoors. Not keen on fire outdoors unaccompanied and there is no cover from rain.

Thank you!!!

Il feel so much happier having a backup solution and can offer a warm place to neighbours if needed. 

lohr500

According to a Google search, 1 litre of diesel has an energy content of 10kW.

So if the diesel heater you are looking at really can produce a sustained 8kW heat output, then it is going to consume at least 0.8 litres per hour . In fact I suspect it will consume more, because some wasted heat will be lost through the exhaust system.
Probably better to assume it is going to use close to 1 litre per 8kwH output. A lot more than the stated 0.24L/H.

I would be very sceptical of those quoted consumption figures. 

I would also worry about ensuring that any diesel heater has adequate provision for the exhaust gasses otherwise 
it could prove fatal. I know they are used in off grid motorhomes and for warming truck sleeper cabs so I guess if installed correctly they should be safe.

I don't think the power consumption will be massive as presumably there will only be a short duration lighting circuit and then a low wattage fan to circulate air through the heat exchanger element, plus a minimal requirement for the control system.

Another option could be a bottled gas heater, which range in price significantly depending on if you go for the open flame or catalyst versions. A problem with bottled gas heaters is that for every litre of gas you burn, you get a litre of water vapour in the room. This can add to condensation issues. The bottled gas heater I had was self contained and needed no electricity supply.
Again, they need to be used with care in a well ventilated room to avoid the risk of carbon monoxide poisoning.

pluto2010

According to reviews some agree with the consumption (Vevor heaters). 
I would imagine this is due to heating a small space so it quickly drops to a lower consumption level.

I have looked into gas heaters, my flat had a massive mould issue when I moved in, I've sorted with ventilation and dehumidifier.
It is a good option though for emergencies.
£130 for a 4.2kwh from a good supplier + gas
15kg £60 gas would last 50 hours on max. £1.20 and hour on max
*would windows locked onto vent mode be enough ventilation I wonder. 

victor2

It does seem difficult to find out how much electrical power diesel heaters require. If you see a possible candidate, try contacting the manufacturer directly to find out. This article is from a US camping website, but gives a few ideas and it appears that the maximum electrical load once running should be no more than 2A from a 12V supply, so 24 watts at the most.

QrizB

pluto2010 said:

Problem: Apart from gas being blooming expensive, if the electric goes there won't be any heat.

Even at 10p/kWh, mains gas is still cheaper than most other non-bulk sources of heat.

pluto2010 said:

-Diesel heater, I'm looking at a 8kwh diesel heater, this is where I need help. The diesel heater I'm looking at is 8kw heater consuming 0.1-0.24 L/H.
*These require a 12v supply, I'm unable to find much info on how many watts at 240v they use though?  I'm thinking in a emergency plugging into the UPS 3 pin outlet and trying to calculate run time.
8kw @ 0.24L/H, diesel@£1.90L = £2.37 For 5 hours at max 8kw.
*What am I missing, why is it cheaper than gas combi buy a fair bit?

Do you mean a diesel heater like these?

https://www.ebay.co.uk/itm/224553891949

https://www.amazon.co.uk/dp/B08L4QKLPJ

As others have already said, a litre of diesel contaiins 10kWh of energy and with diesel at £1.80 a litre that's 18p/kWh, which is almost twice the 10p/kWh you're paying for mains gas.

There's also the matter of installation. Those heaters all require an external air supply and an external flue, which means a hole in the wall (or something similar) - you can see the two smaller-bore flexible pipes pictured in the kit of parts for each listing I've linked to.

£130 for a 4.2kwh from a good supplier + gas

15kg £60 gas would last 50 hours on max. £1.20 and hour on max

LPG contains 14kWh per kg. If 15kg costs £60, that's £4 per kg or 28p/kWh, almost three times as expensive as mains gas. It is however a safe-ish option for backup heating, provided you keep your flat well ventilated.

Are there any other options that are possible that can run with no/very little electric?

Do you have a mains gas stove/hob/oven? Does it still work if the power is off? Hot water bottles, together with a blanket, work well to keep a person warm.

shinytop

The power needed to heat your living room will be a lot less than 8kW,  You can work out your gas CH radiator output from the size of the radiator and the flow temp if you know that and you only have to match that.  Maybe a diesel heater is overkill as it won't be used that much and a bottled gas one would be more practical, safer and less messy.  Even condensation from a few hours every now and then wouldn't be a problem.    

ariarnia

shinytop said:

The power needed to heat your living room will be a lot less than 8kW,  You can work out your gas CH radiator output from the size of the radiator and the flow temp if you know that and you only have to match that.  Maybe a diesel heater is overkill as it won't be used that much and a bottled gas one would be more practical, safer and less messy.  Even condensation from a few hours every now and then wouldn't be a problem.    

yes. our wood stove is a 4kw model and heats most of our down stairs and the room directly above quite easily when used for 3 or 4 hours in the evening (at current temps. obviously more heat is needed to maintain a temperature when its colder). 

drsquirrel

Why not use the UPS to power the boiler?

Also 6600W (6.6kW) is not a small UPS, is that figure a mistake?

Being "off grid" isn't really going to be cheaper than on grid. Protecting against power cuts shouldn't be in the same discussion as saving money imo.

Apodemus

drsquirrel said:

Why not use the UPS to power the boiler?

Also 6600W (6.6kW) is not a small UPS, is that figure a mistake?

The original post said 1000va/6600W.  Since va=W (ignoring the power factor), it seems much more likely we are talking about a 1kW UPS.

chris1973

Be careful when extending the run time of an off-the-shelf UPS, generally the built in batteries it was designed to use will only run the system for a maximum of say 15 - 30 minutes, in which case in order to achieve a cost effective BOM and compact unit its suffice to say that the design of some aspects of the cooling and component choices have possibly all been selected with the same limited run time in mind. 

Extending the run time, by replacing the built in SLA with higher capacity leisure batteries, meaning the original design can run on a continuous duty cycle for hours rather than the minutes the design Engineers originally intended it to run for, can result in things getting toasty, especially at maximum load, resulting in burnt out components, damage to the UPS, or possibly even a fire risk.

Usually the charge rate from the UPS to charge the internal SLA pack is limited to an amp or less, which is no good for charging 200 - 300AH worth of leisure batteries, so the internal charge section of the UPS would need to also be disabled, and a proper charger purchased.

If you are serious about having such a back up system, then don't do it with a series of half measures - ring fence your future reliance on them with a suitable budget. Buy a proper inverter designed for continuous duty and power it from decent leisure batteries.

Also look up the laws surrounding Diesel for domestic heating, they changed back in April. You may still be able to heat a domestic household using red, rather than white diesel and that means £1.10 as opposed to £1.90 a litre.

If not, see if you can get a version of these heaters which burn Kerosene instead of red diesel, this is heating oil and is legal for home heating use. Prices for heating oil are on the way up, but you should still be able to find a fuel merchant selling at between 85p and 95p a litre, which is 8.5 - 9.5p per KW/H before working out efficiency losses.

Reed_Richards

In our old house we installed a mains gas fire in the living room.  This required no electricity so we could use it in the event of a power cut.  The gas pipe was run around the outside of the house from the boiler.  I can't see why this is not being considered as an option.