No Gas - What to use?

[richo106]

Hi

 

I complete on a run down 1960s bungalow next week, it hasn't been lived in for 10 years. Due to funding/mortgages the main bulk of the extension will be done in a couple of years. Short term I will be making it livable

 

The village the property is located has no mains gas so we need to find alternative solution

 

Currently it has a VERY old oil fired boiler and hot water tank, the tank is metal and not the bunded metal type. My first thought was to get a new oil boiler ASAP and then hopefully the tank will last until we do the main work when I will reposition and change the tank.

 

I've also looked a little bit into Ground source heat pump but a couple of things put me off, we are wanting WET underfloor heating downstairs but not upstairs as we much prefer carpets. We like the combi boiler for instant hot water. The main things are the installation cost and amount of room it will need t compared to a oil fired combi boiler

 

The size of the plot of 1500m2 so I do believe we have enough area to install the loops

 

I was just wondering if any had any advice/opinions on this. I have do a few renovation projects but nothing on this scale especially with no mains gas and Underfloor heating

 

All help and advice greatly appreciated

 

Many Thanks

[IanR]

Hi and welcome.

 

I'd suggest looking at an ASHP. I assume you will be addressing insulation and air tightness, so have the opportunity to reduce heat loss. ASHP require lower capital than GSHP and are fairly similar in performance. RHI is running until next March, so you'll need to be quick if you wish to take advantage of it.

 

Are you aware of the possible reduced VAT rate for renovating empty properties? It's worth looking in to it if you are not.

 

You should also be aware of changes to Building Regs for next year that require the heating and hot water system to be designed for "low temp". Even if you start this year, it's definitely worth considering a system boiler and hot water cylinder to future proof your home.

 

 

[joth]

12 minutes ago, IanR said:

Are you aware of the possible reduced VAT rate for renovating empty properties? It's worth looking in to it if you are not.

 

Just to emphasize this: it's worth looking into (15% saving on all the project costs) but there are severe restrictions: the property must be unoccupied for 2 years straight right up to the day the work starts, and all work must be done via a single VAT-registered contractor (as they apply the discount in their bill, there's no claim back)

 

We missed out on this because (a) we thought our house was only unoccupied for 1 year prior to completion (it was actually 2), (b) we had no documented evidence of how long it had been unoccupied (council tax discount etc is the best for this), and (c) we moved into it on completion day, resetting the clock.

 

 

If you want instant demand-heated hotwater, and not interested in (substantially) improving insulation of the property, an oil combo seems the only sensible choice.

 

 

[IanR]

3 minutes ago, joth said:

If you want instant demand-heated hotwater, and not interested in (substantially) improving insulation of the property, an oil combo seems the only sensible choice.

 

Agreed, heat pumps require a hot water cylinder to provide sufficient hot water.

 

My concern is the mood music from the government is changing from carrot (RHI) to stick (Building Regs) with regards zero carbon heating systems, and the stated annual target of 600,000 HP installs by 2028 will only be achieved with a large stick in the retro-fit sector.

 

If you need to replace a boiler after 2028 I feel you will be strongly encouraged not to go with gas or oil. Having to retrofit a HW cylinder, UFH, larger rads etc. etc. will require a more significant tear up.

[Lorenz]

We were looking at air source heat pumps, when we lived on the Baltic and knew people who had moved onto them and were happy, did not meet anyone who was happy with ground source, even people selling and fitting them!  

What about an induction system for hot water?

[PeterW]

ASHP will do all you need here - big DHW tank, oversize the upstairs rads and then use UFH for the rest assuming you’ve got decent insulation levels. 
 

Any option with PV on the roof ..?

[SteamyTea]

Welcome

I am interested to know why you looked into a GSHP?

 

Three things, with a 'system' type boiler, which a HP is, DHW is stored in a cylinder, ready for use, so no waiting, and you can get very good flow rates.

An UFH installation requires extra insulation under it, more than building regulations suggest.  This is because the floor will be at 35 to 40°Cm rather than about 18°C, but the ground will be at the same temperature ~10°C.  It is the temperature difference that is important.

Finally, it does not matter what temperature the heating system works at, the energy needed to heat a building to the desired temperature will be the same.  Power, Energy and Temperature are different things.

 

Reducing thermal losses means you can use a smaller system, most heating systems are sized for DHW demand and not space heating, but an ASHP is designed to be a little larger than your peak power demand.  This keeps the Coefficient of Performance (CoP) in a more efficient place.  Then there is the manner in which they are used, they are kept on, chugging away, rather than blast out heat, turn off for a while, then blast again.

Modern ASHP, if designed and installed correctly, are not expensive to buy or run, nor are they noisy.

Edited June 22, 2021 by SteamyTea

[Ferdinand]

Fabric First. And don't skimp on the standards.

 

Make damned sure that you do first the things that you cannot do later such as under floor insulation, walls etc.

[Mr Punter]

If you focus on insulation and draft exclusion, your space heating needs can be significantly reduced.

 

Maybe stick in some electric panel heaters for a quick fix.

 

If you can stretch to an ASHP it may be a good bet, especially with underfloor heating.

[Temp]

7 hours ago, IanR said:

Are you aware of the possible reduced VAT rate for renovating empty properties? It's worth looking in to it if you are not.

 

+1 If its been empty 10 years you can get it zero rated (you pay builders 5% VAT and reclaim it from HMRC). Must not move in before work starts but can move in the day after.

[PeterW]

Just watch what HMRC need for proof of “empty” - if council tax has been paid then they may not accept it has been unoccupied so they don’t count that as a valid reason even if it wasn’t someone’s primary residence. 

[joe90]

15 minutes ago, PeterW said:

Just watch what HMRC need for proof of “empty” - if council tax has been paid then they may not accept it has been unoccupied so they don’t count that as a valid reason even if it wasn’t someone’s primary residence. 

But in Bristol you still pay council tax on empty properties!!,!, In Devon you only get 3 months grace for being empty.

[A_L]

3 hours ago, SteamyTea said:

This is because the floor will be at 35 to 40°Cm rather than about 18°C,

 

The floor will not be at these temperatures. A well insulated building can be heated with a floor at 2-3°C above the required air temp. The fluid in the UFH pipes may be at these temperatures but 5-7°C above the floor temperature would normally be sufficient for continuous heating. Yes heat losses will be higher than an unheated floor but only by 20% or so.  

[joe90]

4 hours ago, SteamyTea said:

This is because the floor will be at 35 to 40°C

eh?, I run my UFH water at 25’.?

[ProDave]

58 minutes ago, joe90 said:

But in Bristol you still pay council tax on empty properties!!,!, In Devon you only get 3 months grace for being empty.

And in Scotland you pay double on an empty property.

[SteamyTea]

2 hours ago, joe90 said:

I run my UFH water at 25

You have a new design house, the UFH was designed in from the start.

An old place, with a 'normal' plumber specifying UFH, it would run the system at a higher temperature.

Edited June 22, 2021 by SteamyTea

[richo106]

Thank you all for the comments

 

After having a think I think we will stick with oil combi boiler for the medium term but when we do the extension/build we will ensure it done to high standard insulation wise and leave enough room/provisions in the 'boiler room' to have another system installed.

 

With regards to running UFH heating off an oil fired combi boiler is this possible? Would i need some sort of back thermal store (i believe its called) to make this work.

 

The house will hopefully be 4 maybe 5 bed room when complete...is a combi boiler suitable to heat this and feed an ensuite and main bathroom.

 

Happy to install electric showers if they are some good ones available (any recommendations?)

 

Thanks again to all replies very helpful

[joe90]

Just now, richo106 said:

With regards to running UFH heating off an oil fired combi boiler is this possible? Would i need some sort of back thermal store (i believe its called) to make this work.

Yes you need a buffer tank to stop the oil boiler from short cycling (switching on and off quickly) then blend the output down to UFH temp.

[Thedreamer]

21 hours ago, SteamyTea said:

 This keeps the Coefficient of Performance (CoP) in a more efficient place.  Then there is the manner in which they are used, they are kept on, chugging away, rather than blast out heat, turn off for a while, then blast again.

Modern ASHP, if designed and installed correctly, are not expensive to buy or run, nor are they noisy.

 

I’m sure this has been covered previously but if you insulate/airtightness a property to a good standard your heating demands will be low. As you are then likely to need your space heating when temperatures are low, say 0 celsius, presumably your COP efficiently will be low, 2.5. If you obtain COP 2.5, then surely when combining the capital cost with the unit of electricity the cost is really that much better compared to direct electricity heating.

 

I’m still try to understand the logic with external air source heat pump for a self build. You never achieve an optimum performance as in the summer when air temperature is higher you don’t need the space heating you have the higher COP but not full use of the capacity but in the winter you have full use of the capacity but a reduction in COP. I have heard of members running them in reverse for a slab perhaps that is a bit I am yet to understand.

[joth]

Absolutely, a "true" passive house just needs no ASHP,  just few human bodies to heat it, right?

At a more achievable level, a lot of people here see the economics of ASHP don't add up and go for a Willis heater for their wet UFH instead.

Others want to protect themselves more against future energy price increases, or have non-financial reasons for going with ASHP (from reducing carbon output to enabling summer time cooling)

Horses for courses.

 

It's definitely not one-size-fits-all, not in the way that combi boilers are currently pitched. However, as sale go up, prices will come down, and it'll slowly capture more market share as the economics will gradually swing more in favour. 

 

 

Edited June 23, 2021 by joth

[IanR]

1 hour ago, Thedreamer said:

As you are then likely to need your space heating when temperatures are low, say 0 celsius, presumably your COP efficiently will be low, 2.5. If you obtain COP 2.5, then surely when combining the capital cost with the unit of electricity the cost is really that much better compared to direct electricity heating.

 

I’m still try to understand the logic with external air source heat pump for a self build. You never achieve an optimum performance as in the summer when air temperature is higher you don’t need the space heating you have the higher COP but not full use of the capacity but in the winter you have full use of the capacity but a reduction in COP. I have heard of members running them in reverse for a slab perhaps that is a bit I am yet to understand.

 

If you include the hot water a heat pump provides, it may make more sense. Based on compressor time, HW production is two thirds of the work my ASHP does. Also, COP for space heating would rarely drop below 4.0 on my HP, average for space heating would be above 4.0.

 

1 hour ago, joth said:

Absolutely, a "true" passive house just needs no ASHP,  just few human bodies to heat it, right?

 

Not quite, but in theory it brings the space heating down to what could be provided by an in duct MVHR electric heater. A solution for DHW is still required though.

Edited June 23, 2021 by IanR

[SteamyTea]

1 hour ago, Thedreamer said:

As you are then likely to need your space heating when temperatures are low, say 0 celsius, presumably your COP efficiently will be low, 2.5.

There seems to be some misunderstanding about 0°C.  Much better to calculate on the kelvin scale, then you will see how little the CoP actually drops.

The biggest enemy is really humidity at ~4°C, this is when air will have its highest humidity levels (note humidity not relative humidity), this is why ASHPs are oversized, once above or below that temperature, the CoP often rises.

They work by extracting energy by cooling the air that passes though them, if they cool some water, then they get extra energy.

If you had to choose a temperature scale the zero point should be the lowest temperature that the refrigerant gas can go to, but that is all a bit academic.

 

But as @IanR points out, the DHW is the real challenge, not the space heating.

[SteamyTea]

1 hour ago, joth said:

It's definitely not one-size-fits-all, not in the way that combi boilers are currently pitched.

Nor are combi boilers, most people take very little interest in the sizing of them, or the flow rate they can produce.

[joth]

5 minutes ago, SteamyTea said:

1 hour ago, joth said:

It's definitely not one-size-fits-all, not in the way that combi boilers are currently pitched.

Nor are combi boilers, most people take very little interest in the sizing of them, or the flow rate they can produce.

 

Quite true. I think it's useful to bear in mind this is how they're sold though, as it explains the mentality most are coming into ASHP with.