more UFH questions, calcs?

[albert]

 I'm sure some of these question have been answered but as I'm now building my own house whilst running my business and helping with a  bambino  the valuable research time is suffering.  !!!  Apologies in advance

 

I'm building a large open plan New build sap rated at 79-8o ish  I'm on a very tight budget due to the size 300m2 . I plan to live here long term so want a decent system.  Its a big house but we are only 3  so usage will mainly be  in certain areas. 

I plan to zone the GF in 3 zones with UFH throughout. my question are:

-My plumber is suggesting negligible cost differences between ASHP and an efficient oil set up and so far I am beginning to agree.

 

-I have a large vaulted hall way and feel that heating upstairs will rarely be used so was thinking of using rads upstairs to be used as required rather than the UF I was planning . I think significant saving s could  be made even if we used the ASHP rads. (saving in labour ,insulation and  UFH materials)

 

-The UFH is in a 150 slab , I'm amusing it will take longer to heat up and cool down  but  are there any other disadvantages. I am going to insulate edges of slab with 75 mm as i can cover that with the build up.

 

- Is it possible to calculate the pipe spacing yourself for UFH, I was assuming that tight spacing say 100mm would give me a lower running temperature of the system.

 

 

Thanks again 

 

A 

 

 

 

 

[PeterW]

5 minutes ago, albert said:

My plumber is suggesting negligible cost differences between ASHP and an efficient oil set up and so far I am beginning to agree.

 

Based on...?? 

 

ASHP can be self installed and had for change of £3k all in. Oil boiler and tank are Oftec install and a push for £3-4K.  Oil boiler needs an annual service, ASHP does not. 

 

With a 150mm slab you have already created a big heat sink that is ideal for overnight or E7 heating. This should get your heat cost down to around 2p/kWh so ask your plumber to match that with oil and then see where it goes. 

[MikeSharp01]

2 minutes ago, PeterW said:

E7 heating

Did you mean to add "via the ASHP" Peter as a Willis type arrangement is also possible on E7?

[albert]

I am open to suggestions my quote was from NU heat  the supply for the UFH was 6.5 K alone.  I like the idea of  air source  but concerned about the electricity costs, I don't have PV at this stage. Is there a supplier I should be talking to direct? 

[PeterW]

48 minutes ago, albert said:

I am open to suggestions my quote was from NU heat  the supply for the UFH was 6.5 K alone.  I like the idea of  air source  but concerned about the electricity costs, I don't have PV at this stage. Is there a supplier I should be talking to direct? 

 

Wunda Trade - 240sqm kit for just over £1k

 

will do your design for you and provide all the bits. 

 

Nu-Heat can be a bit .... pricey.... 

 

2 hours ago, MikeSharp01 said:

Did you mean to add "via the ASHP" Peter as a Willis type arrangement is also possible on E7?

 

Yep sorry !! 

[albert]

OK great Thanks I will give them a call today

 

 

[ProDave]

My main concern with oil is the volatility of the price,  it might seem reasonably priced now, but a few years ago it was not, and no doubt again in the future it will spike up.

 

It sounds like your house it well insulated so it should not need much heat input.  What does your SAP calculations give as the maximum heat input demand to the house?

 

[SteamyTea]

You can always fit PV at a later date, though it need not cost more than a tiled roof.

Again, parts can be self-sourced.

300 m² is a big place, about 6 times the size of mine. So without a lot of insulation under the UFH and perimeter, you stand to loose a lot of energy.

Is it realy any cheaper to fit radiators upstairs, rather than UFH into the floor? You can use a different spacing for the pipes to limit the energy transfer.

Have you done the heat loss calculations and DHW usage yet?

[connick159]

On 31/08/2019 at 10:18, PeterW said:

 

Based on...?? 

 

ASHP can be self installed and had for change of £3k all in. Oil boiler and tank are Oftec install and a push for £3-4K.  Oil boiler needs an annual service, ASHP does not. 

What  3k!!!

We just got a got for 11k. How is that possible?

[jack]

6 minutes ago, connick159 said:

What  3k!!!

We just got a got for 11k. How is that possible?

 

Where does the quote say the money goes?

 

Here's the current version of the 5kW Panasonic ASHP we installed a few years back: https://www.easyheatpumps.com/product/panasonic-h-generation-high-performance-55c-monobloc/?attribute_models=WH-MDC05H3E5

 

Just over £2000 (and you'd reclaim the VAT back on a new build).

[connick159]

Ah ok. Our quote was for a pump plus a water tank plus installation. 

Stiebel eltron was the brand.

11k still seems pricey. Can't get vat back as an extension not new build.

[PeterW]

1 hour ago, connick159 said:

Ah ok. Our quote was for a pump plus a water tank plus installation. 

Stiebel eltron was the brand.

11k still seems pricey. Can't get vat back as an extension not new build.

 

300 litre UVC is £875

9Kw ASHP can be had for £2500

Pipe and bits £500

2 days to install and commission ..? 

 

£5-6k tops, more than that and they are taking the..... 

[connick159]

15 minutes ago, PeterW said:

 

300 litre UVC is £875

9Kw ASHP can be had for £2500

Pipe and bits £500

2 days to install and commission ..? 

 

£5-6k tops, more than that and they are taking the..... 

Thanks Peter,

This looks more attractive than 12k!

Are all the brands decent these days or are there tried and true ones to stick with?

Eg. Some of them look like reverse cycle air cons like back in Oz while others are massive things.

Edited September 2, 2019 by connick159

[SteamyTea]

52 minutes ago, connick159 said:

Some of them look like reverse cycle air cons

That is because they are.

Just a matter of where you stand really.

[Jeremy Harris]

2 hours ago, connick159 said:

What  3k!!!

We just got a got for 11k. How is that possible?

 

 

I bought a brand new brand name monobloc inverter controlled ASHP and control interface, a 6 to 7 kW model, for £1,700 delivered.  Cost another ~£300 in installation parts, plumbing, etc and took me less than a day to install.

[albert]

Thanks for the advice.

Wunda have priced the UFH at 3k for both floors that's half my plumbers merchant quote. The upstairs is £ 1300 I'm not sure of the cost of ASHP rads but I will look all this up maybe not a lot in it?. I would like to go to ASHP as I am sure its better for the environment I just don't know enough about it .  My merchant also told me it can not  be used to cool the house . I read here that it could is there a lot of additional cost evolved?  I'm waiting for further quotes  and I will look up the heat imput etc tonight.

[PeterW]

1 minute ago, albert said:

My merchant also told me it can not  be used to cool the house . I read here that it could is there a lot of additional cost evolved?

 

Merchant speaks with forked tongue ....

 

And not a massive amount of cost, just make sure you get an ASHP that supports cooling. 

[albert]

 

Todays prices FYI 

 ::Samsung 19Kw ASHP with Unvented HW Cylinder and components   £9177   against Grant Vortex 26/36 Oil System Gledhill 300ltr tank etc  £3500.  ex VAT

 

 

 

[Alexphd1]

https://www.greenwayenergyltd.co.uk/product-page/samsung-16kw-monoblock

 

That's inc vat.

 

Is this a RHI  installation? Is that grant and samsung price installed, do you already have a oil tank?

[PeterW]

23 minutes ago, albert said:

 

Todays prices FYI 

 ::Samsung 19Kw ASHP with Unvented HW Cylinder and components   £9177   against Grant Vortex 26/36 Oil System Gledhill 300ltr tank etc  £3500.  ex VAT

 

 

 

 Why the 19Kw ASHP ..?? If this is a new build then unless it’s a 7 bed mansion you cannot have 19Kw heat loss from that. 

 

Have you done the heat loss calcs..??

[albert]

no plus vat . it doesn't sound like rhi worth the hassle. 

[albert]

I have this SAP report but I am not an expert in deciphering the information. !!

2018 Full SAP Calculation.pdf

[PeterW]

15 minutes ago, albert said:

I have this SAP report but I am not an expert in deciphering the information. !!

2018 Full SAP Calculation.pdf 130.35 kB · 3 downloads

 

Not wanting to question this but ... you’ve failed design SAP..????

 

Your design doesn’t meet DER / TER, so what are you having to do about it as your wall and floor construction doesn’t meet the standards. 

 

Ignoring that ... your worst case Heating need is 4140Kwh in a month, so that’s a maximum of 8.6Kw/h based on a percentile based value with 24 hour running of the heating. 

 

So a 10Kw ASHP can do this, why the 19Kw..??

 

I would also look now at spending the £6k difference between oil and ASHP on the external wall insulation and get that SAP number up the scale and drop the heating requirements. 

 

@JSHarris   @ADLIan  have I missed anything in that SAP report ..??

 

[A_L]

7 minutes ago, PeterW said:

have I missed anything in that SAP report ..??

 

Although no MVHR using default (15m3/m2/hr@50Pa) ventilation rate seems excessive

Edited September 6, 2019 by A_L

[Jeremy Harris]

9 minutes ago, PeterW said:

@JSHarris   @ADLIan  have I missed anything in that SAP report ..??

 

 

Not missed anything, looks like a fail to me.  My guess is that the oil heating is one reason, as a high fuel factor for oil won't be helping.   The space heating requirement is pretty massive for a house of this size, it's around ten times higher than ours, so improving insulation would help a fair bit.  The wall, floor and opening U values look high, should be pretty easy to get the floor and opening U values down to something a bit more reasonable, I'd have thought.  I'd not contemplate fitting UFH with that high a floor U value, either, as the losses to the ground will be relatively high.