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Unexpected Gas Supply


Andrew

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Before we started, in fact, before we bought the plot I obtained plans from all the utility companies and the nearest gas main was a very long way up the road. No problem, we made all of our plans based  on only having electricity. That included ASHP for UFH and hot water with an immersion boost. We were pleased that there is potential for lower carbon emissions with an ASHP, especially as the grid continues to de-carbon. We had an as-designed SAP done, with an A 94 rating including the ASHP, our Ecology mortgage has a discount if we achieve this. The plan was made, all was good. 

 

So I was talking to my neighbour the other day (who is building on a plot next door) and, with a glint in his eye, he said I'm getting a gas supply. I immediately asked the obvious questions, "How much?" . "£800" he said, clearly delighted with this small victory. Turns out a couple of new builds up the road had paid mega bucks to bring the gas main down the street and as such my neighbour had benefitted with a relatively modest cost for his gas supply. 

 

Now this got me thinking, surely given that they will need to extend down to my neighbour, my cost to connect gas should be similar to his, so I've submitted an application for a quote. But, I'm really in two minds - I was set on having an ASHP and whilst I know the running costs with gas will be lower, the higher environmental cost really troubles me. Moreover I think there's an element of being reluctant to change plans at this late stage. I have already buried all the ASHP ducting and piping through the slab, researched and selected the ASHP unit and supplier, the plumbing tender has gone out with the ASHP in it and our accepted electrical quote includes connecting the ASHP up. 

 

So I'd welcome any thoughts, am I just been too inflexible, unwilling to make a change at this late stage or is there merit with sticking with electricity only. What's the likely impact on the SAP assessment, will using a gas boiler lower our rating massively?

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I'd generally avoid making decisions based on what it does to the SAP rating unless your financing is dependent on it. As has been discussed elsewhere on here, SAP has some flaws in low energy housing.

 

The only benefit you mentioned in using gas is the potentially lower running cost, but even that is only based on current prices and you can't guarantee it would continue. 

 

Like everyone on here, we've made many decisions based on what's important to us, rather than trying to cost-benefit everything to death. Assuming your house is fairly well insulated I'd imagine your all electric costs would be pretty low in an absolute sense ? If that's the case, I'd not be considering gas.

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I am in the planning stage for 3 new flats which will be build to let.  I really wanted to go no gas but there was no way to sensibly achieve it without impoverishing myself and the tenants.

 

For a house, with the space for tanks and plant it must be a closer call.  Combi gas boilers for me though.

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Install the gas for now, and leave it all set up ready in anticipation of the fitting of an ASHP later down the road if the numbers make more sense then. If it's not a massive property you could get away with a decent high-flow combi boiler at £1500-£1800 plus fitting. Do you have rads or UFH?

Most other M&E's I've spoken with still advocate using gas if it is available.... Your conscience is your's to deal with and your's alone. Also your money is your's to spend, and not others who may aspire to better things ( when it's not at their expense ).

Do what is right for your budget and expected living costs, and if it becomes viable later, you or a new owner could retro fit the ASHP with ease.  

Edited by Nickfromwales
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1 hour ago, Andrew said:

What's the likely impact on the SAP assessment, will using a gas boiler lower our rating massively?

 

SAP is a COST index, given the current price of gas vs daytime electricity switching to gas could increase your SAP score.

 

https://forum.buildhub.org.uk/topic/11185-what-is-the-effect-of-epc-changes/?tab=comments#comment-188312

 

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Get the gas piped to the property, you don't actually have to get the meter fitted and it made live.

 

My parents did that (along with ducts for all the other services) to one of the outbuildings when we did some sewer works.

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Interesting comments, thanks.

 

Its quite a big house, 320 m2 with 6 bathrooms, so a combi probably isn’t going to do it. We’ve UFH throughout the ground floor but no plans for radiators upstairs. We’ve just finished the roof, doors and windows are going in now, so could easily change plans at this point.

 

Even keeping the unvented cylinder, a decent sized system boiler seems to be less than half the cost of the ASHP, so I’m sure there’d be a saving on the build cost as well as the ongoing running costs.


We’re not in passive house territory, although the house will be fairly well insulated (it’s a 140mm open panel timber frame fully filled with frametherm + 50mm PIR on top across the studs) and good airtightness. According to the SAP calcs we need about 12,000 kWh of heat input per year for space heating and hot water, so with some rough calcs using a very conservative COP for the heat pump, I reckon there’s about £200 annual saving for gas.

 

But as some have said it’s not just about the pounds and pence and electric has much more potential to allow us to meet some of the environmental goals of the build. 
 

Hopefully the gas connection quote will come back really expensive and it’ll be decision made!

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34 minutes ago, epsilonGreedy said:

I though SAP was an eco goodness index that does not track cost directly?

 

Not the main SAP Index, but there others within SAP that have 'eco goodness'. Fabric Energy Efficiency (FEE), Environmental Impact Rating (EI), Dwelling Emission Rate (DER)

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39 minutes ago, Andrew said:

Hopefully the gas connection quote will come back really expensive and it’ll be decision made!

Lets wait and then make some further recommendations. Your build sounds like it could easily accommodate an ASHP and it would be better suited to drive that type of heating.

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  • 8 months later...

I would try and have a small plant room so that changes to any type of heating system are minimised to the whole house.

 

a few spare ducts from the plant room to outside for future will save a lot of grief.

 

oh and a drain connection too!

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I didn't bother in the end, mainly as budget is under stress and whilst the quote was only £1500, all these 'only' 1500 quid items add up. I have laid a duct from the plant room under the driveway to the boundary so if the ASHP turns out to be a disaster we can connect it without digging up the drive. 

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Just now, TonyT said:

Sure, but if the condensate is going outside you have to increase the diameter of the condensate pipe to prevent freezing.

 

 

Good to hear, I thought I had a made a design mistake. When I first read your post I began to think that a hydrogen boiler might generate a lot more water and require special drainage arrangements. 

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