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Burning debate at present as to how I heat my house. Considering an ashp bit not sure it is worth the outlay. Only other option is oil. I have one quote in at the minute and there is probably 4k or so difference between the 2.

 

Is an ashp that much better with ufh. 

 

What should I be looking out for? All advice and opinions welcome. No rhi available here in NI either.

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Which ASHP are you looking at and what is the heat load ..?? You can get up to 12-14kw ASHP for less than £2k and they are pretty much self install. Oil is much more than that and you have the ongoing service costs etc. 

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As Peter says it depends on what kW you are going to need. If like most of us seem to be on here, you are building a really well insulated house, then ASHP is a safer bet. Oil prices are only going to have one general trend in the years to come despite fluctuations, and if you are able to have solar PV you are offsetting some of the electricity your ASHP will use, making it win-win.  Even without being able to have solar PV on our build we are going for ASHP over oil or LPG (no mains gas where we are). 

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Are you near the sea?  I believe that some ASHPs may not cope well with a lot of salt water.

 

ASHPs, in general, work well with UFH because it only requires relatively low temperatures, especially in a well-insulated house.  They can be less suited to - or at least less efficient for - DHW production.

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3 hours ago, PeterW said:

Which ASHP are you looking at and what is the heat load ..?? You can get up to 12-14kw ASHP for less than £2k and they are pretty much self install. Oil is much more than that and you have the ongoing service costs etc. 

Unit I have been quoted for is a Hitachi yutaki 14kw supplied installed and commissioned it is priced at £7k! Not sure I would want to self install.

 

@jack no not near the sea, in the hills.

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Again what is said above regarding is your house suitable for ashp.

sourcing the ashp yourself and finding a decent plumber?sparkie to connect it up should be cheaper than oil boiler/oil tank installation but doing this you are unlikely for rhi paymnents. Another point to consider is repair, i would think you would be easier and quicker to find a guy for your oil boiler than heat pump. 

I am going down the ASHP route.

quick heads up there is a nice calorex 15kw mono block ashp sitting on ebay at around £1k might be worth a look!

just came across a gledhill thermal store on ebay aswell!  

Edited by Alexphd1

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I came at this from another direction.

 

First question is, what's the maximum demand for Domestic Hot Water? for many of us on the forum its two concurrent showers and maybe a hot tap.

 

That gives you two options to deliver it:

  • either from a single domestic boiler rated around 28kw
  • or from from a tank full of the stuff (which could be a Thermal Store or a DHW Cylinder)

 

You get the energy into the tank using electrical energy from your solar panels and/or ASHP. Typically you bring the tank up to the temperature you want by means of a smaller capacity boiler. (You could actaully keep the tank at a lower temperature level and use electrical top up heaters for your showers and baths).

 

There's a significant disadvantage to tanks full of hot water however, and that's how to stop them leaking heat 24x7. JSHarris had this issue - he tried applying additional insulation but that didn't work and he still had an overheating problem - especially in summer. At that point he took the tank out and replaced it with a Sunamp phase change energy store, (which is very similar in function to a tank of hot water but much smaller and leaks a lot less heat).

 

If (like me) you decide "my house is very well insulated. I am not going to need a great deal of energy to run it. So instead of focussing on using the minimum amount of energy I will take the simpler option and stick a boiler in" then the 2nd question becomes "what fuel?"  I too don't have mains gas but I have cooked with and been heated by cylinders of LPG for many years and I'm perfectly comfortable with it as a fuel. My last LPG Boiler was still running strong after 14 years with (ahem) very litlle servicing. NickfromWales has posted several times on what in his experience the best boilers are, and they support LPG out of the box. I also have to stay I've also lived with oil boilers and am not impressed. Noisy, smelly things, and definitely no good for cooking! So a 28kw Vaillant LPG Combi boiler and a gas hob in the kitchen it is for me.

 

That then leaves the question of Solar Panels. If flogging the generated energy back to the grid has become uneconomic and you don't have a hybrid car to charge - in winter and the colder periods of spring and summer, you use it to heat the house. That leaves summer - and then its an economic question - shall I spend around £1.5 k on a Sunamp to store the energy and reduce my water heating costs?  Even run an air conditioner to cool me down?

 

One final point about the showers. To run two concurrent showers, you really want to install a cold water accumulator (unless you have consistently high mains pressure). The accumulator (c. £500.00) will give you stable water pressure ate all times and this means your boiler will drive your showers (flow rates available on request)

 

Let me emphisaise that the approach I am taking would not be to everbody's liking (the siting and replacing of 4 x 47kg cylinders for example). But I thought that explaining my reasoning would be useful to others.

 

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5 hours ago, vfrdave said:

Burning debate at present as to how I heat my house. Considering an ashp bit not sure it is worth the outlay. Only other option is oil. I have one quote in at the minute and there is probably 4k or so difference between the 2.

 

Is an ashp that much better with ufh. 

 

What should I be looking out for? All advice and opinions welcome. No rhi available here in NI either.

 

Like you, and many others, I've gone round and round trying to settle on the optimum system.  I did consider oil, but concluded it was in the medium to longer term going to cost more to run.  In the end, I've decided to go with an ASHP and 300L cylinder, as this seems to be the best match to my needs / requirements, and is the cheapest to run.  I was seriously looking at the SunampPV and a small ASHP for heating, but the costs were just too high, both capital and running costs.  As others have said, forget about an MCS install, and get your plumber and electrician to do what's required.  

 

3 hours ago, jack said:

Are you near the sea?  I believe that some ASHPs may not cope well with a lot of salt water.

 

Mitsubishi do coastal versions of their range, which is what I've decided to go for. 

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5 hours ago, jack said:

Are you near the sea?  I believe that some ASHPs may not cope well with a lot of salt water.

 

ASHPs, in general, work well with UFH because it only requires relatively low temperatures, especially in a well-insulated house.  They can be less suited to - or at least less efficient for - DHW production.

 

1 hour ago, Stones said:

Mitsubishi do coastal versions of their range, which is what I've decided to go for. 

Last year I went around Penwith taking pictures of ASHPs that are close to the sea (<100m).  None seem to have suffered any serious affects.  That could be because the ones that had are no longer there.

I think the Mitsubishi ones were OK (Lidl in Penzance).

A hunt around the old eBuild forum may find my pictures of them.

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The house will be reasonably well insulated 150-175mm full fill block cavity with air tight measures put in place. Have only contacted one company about ashp and the 7k is what they have come back with which is a split indoor and outdoor Hitachi unit which could be connected to a 300l dhw tank at extra cost.

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4 minutes ago, SteamyTea said:

Are you going for the RHI, that pushes the price of the install up.

We don't have RHI in northern Ireland any longer, over subscribed or the system was worked so withdrew it in Feb this year.

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That Hitachi one appears to be a split unit - needs a refrigeration engineer to fit it if that's the case. 

 

14kw monoblock can be had for less than £3k if you shop around. Your other option (if it's for DHW and UFH) is to use two smaller units and run the curves differently so you can optimise the water temperatures. 

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10 minutes ago, PeterW said:

That Hitachi one appears to be a split unit - needs a refrigeration engineer to fit it if that's the case. 

 

14kw monoblock can be had for less than £3k if you shop around. Your other option (if it's for DHW and UFH) is to use two smaller units and run the curves differently so you can optimise the water temperatures. 

Increased and unnecessary complexity with the split units IMHO. 

Monoblock seems a much better choice to me. 

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+1.  How easy is it going to be getting a refrigeration engineer vs  getting a plumber if there is a problem?

 

 

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This whole subject has been doing my head in for almost 2 years and I've flip flopped on it more times than an MP with a second home!

I've gone from biomass (because in effect the fuel is free to me), then off that as the systems are way too high powered for our design, then torn between LPG for installation and purchase cost (lived on LPG for heating & cooking for years before going to biomass for heating/DHW in our last home) and ASHP. We have more than enough ground for GSHP but crazy installation costs. In the end had to say ASHP to keep our planners happy in the National Park, and keep our renewables bit present as we cannot have panels, though it pains me to have an item in my house that I myself cannot fix in the future (never having paid a plumber in my life except to certify my LPG gas work when selling our last house). At least by not going through RHI we won't be held to ransom on the prices by the approved companies however. We will still be cooking on LPG though. Which kind of means at least there's another heat source in the house if ever we get the winters back where our electricity goes off (was a regular thing here when I was a kid). Once again, learning from the forum will save me thousands!

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I am going ASHP and the comment to me was how often do you need to service a fridge ( same technology!).

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Can I ask a question related to this?

 

I am wiring a new house being built by my plumber friend. He would like to just heat it with an oil fired boiler,. but he says it fails the SAP assessment with just an oil boiler which is why his design SAP says to use a ground source heat pump. he's starting to question me about provisioning the wiring so he can later swap the heat pump for a boiler later on.

 

By why would the SAP fail an oil boiler yet it's okay with a heat pump. Sounds to me like not enough insulation? if so that's not what you want if using a heat pump. 
 

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I'd argue that it's not to do with the insulation, but to do with the temp range of the heat source maybe?

Whats the quality of the build, Dave?

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Does SAP (TER/DER) use primary energy as a fuel source?  If so, that could swing it as our electricity grid is getting less carbon intensive.

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I’m in a similar position to yourself vfrDave.

 

Been torn between ASHP, GSHP and oil (based in NI)

 

Disregarded the GSHP due to initial expense and added expense of having to replace the antifreeze.

 

So made a pro and con list for system oil boiler and ASHP. I have no experience so I wouldn’t take this as 100% correct. Anyone, feel free to point out my inaccuracies.

 

OIL system boiler

 

PRO

-Can be serviced and all plumbers

-Not unusual for a system oil boiler to last 30+ years.

-If heating is required upstairs, standard sized radiators can be used upstairs

-Can probably get away with a smaller UVC/TS as the water could be stored at a higher temperature.

-If anything does go wrong, it is easy to get parts

 

NEG

-Oil can get stole especially if living in the country and out at work during the day

-Oil is and will continue to go up in price

-Need to order oil in advance (need to keep an eye on it that you’re not running out)

-Potential for overheating in summer from UVC/TS

 

 

ASHP

PRO

-potentially better for the environment (based on how your electricity is produced)

-No need to order fuel.

-Potential to install a monobloc yourself (personally don’t know that I could myself though)

-Less likely for things to go wrong?

-works well with UFH

 

NEG

-If heating is required upstairs, larger radiators may be needed upstairs.

-Less common for plumbers to have experience with servicing/ setting up (possibly more expensive to set up)

-I’m not sure that they will last as long as an oil boiler?

-less efficient in colder weather when they will actually be needed.

-Quoted COPs are usually a bit lower than real usage (defrost cycles)

-efficiency decreases when heating water over 40 degrees.

 

 

I have been thinking of and oil system boiler and a TS (I’m also planning on PV) but after looking at my list I am as confused as ever.  Be interesting to see what you decide.

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I'd genuinely like to know why this is even a question. Don't we all agree we should be reducing heat loss to the point that a FF based boiler is way overkill?

 

You still have DHW to consider but we all know there are ways around that (pre heat heat pump, or just E7, plus solar etc, also consider inline instantaneous).

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11 hours ago, Nickfromwales said:

I'd argue that it's not to do with the insulation, but to do with the temp range of the heat source maybe?

Whats the quality of the build, Dave?

It's an "ordinary" timber framed house. The sort of thing I built 13 years ago and wish to improve upon this time around.

 

So blockwork outer skin and render, ventilated cavity. 150mm frame filled with "rockwoll". 50mm kingspan over inside of frame then service void.  Cold roof with "rockwool" loft insulation.  3G Rationel windows so at least he chose well there.

 

His energy assessor says it "fails" the SAP assesment if he just uses an oil boiler.  I will find out more when I see him tomorrow.
 

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Can he not say he is going all electric but put in all what's needed for oil and install it once it's passed.

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