Air source heat pump + ufh costs

jlptheman

Hi all,

I'm currently in the middle of a new build (circa 2800sq/ft bungalow with loft conversion) and I had my heart set on trying geothermal plus underfloor heating. I had a plumber/technician onsite today to inspect and it turns out that the soil is too sandy for the ground source heat pump to be effective.

He suggested air source heat pump and he's gonna do me up a qoute for full installation of ashp + ufh. Hes gonna do me another qoute for the same plus hooking up a back boiler in a log burner/stove to assist during the winter.

What should I expect to pay?

Also any tips or advice would be greatly appreciated.

Thanks,
John

heinbloed

See the previous links about heat pumps.

Expect to have an eternal bill.

There are no Irish heat pumps registered on this registry, despite free for everyone. Some tried but had been strucked from the list providing inadequate and/or obviously false data. Mind the cowboys.

Public HP performance register:



http://www.waermepumpen-verbrauchsdatenbank.de/index.php?lang=en

And a gouverment research project:

Getting warmer: a field trial of heat pumps PDF / PDF's / Media - Energy Saving Trust

And many more if you wish, just check the www.

jlptheman

Hey thanks for the comment.

I was told that it would be only marginally more expensive to run that geothermal.

Given that geothermal is out, what would be the best option for me right now in your opinion.

The focal point for me is running cost..

spcw

PM me and i will send you contact details for a compaany that can do the thermal thing well worth talking to, they also have raidiators that can be run from their thermal panels.

Outkast_IRE

jlptheman wrote: »

Hey thanks for the comment.

I was told that it would be only marginally more expensive to run that geothermal.

Given that geothermal is out, what would be the best option for me right now in your opinion.

The focal point for me is running cost..

I would avoid a air source heatpump i was part of a install where they found it crap the last two winters as it spent a load of time trying to defrost itself every day and the bills were big, not worth it imo .
If you cant get natural gas off of bord gais and the option was oil or lpg, i would personally go for oil and and solar, if i had the option i would love to fit high efficency evacuated tubes for the solar , and connect that and the oil boiler to a buffer tank , that would be a very good setup on that side of things.

Then just ensure the underfloor is zoned properly with good quality digital thermostats in the rooms .

heinbloed

Always ask for a guaranteed maximum electric energy usage of the HP based heating system.
It is no problem for a confident HP manufacturer to give you this guarantee in writing, based on calculations by EN standards.
Every promise in writing, facts and numbers ! Signed and sealed by the HP manufacturer, they have the software.
The cowboys in the trade usually run when asked for such written guarantees.

Contact an energy advisor if feeling incompetent to make a decision. He/she might be able to get you a very good deal, safe and reliable. Or they simply shake their head about the energetic situation of your building.

Invest in knowledge first, then you won't have to rely on 'promises'.

jlptheman

Outkast_IRE wrote: »

I would avoid a air source heatpump i was part of a install where they found it crap the last two winters as it spent a load of time trying to defrost itself every day and the bills were big, not worth it imo .
If you cant get natural gas off of bord gais and the option was oil or lpg, i would personally go for oil and and solar, if i had the option i would love to fit high efficency evacuated tubes for the solar , and connect that and the oil boiler to a buffer tank , that would be a very good setup on that side of things.

Then just ensure the underfloor is zoned properly with good quality digital thermostats in the rooms .

Thanks for the info, back to the drawing board for me then so!

heinbloed wrote: »

Always ask for a guaranteed maximum electric energy usage of the HP based heating system.
It is no problem for a confident HP manufacturer to give you this guarantee in writing, based on calculations by EN standards.
Every promise in writing, facts and numbers ! Signed and sealed by the HP manufacturer, they have the software.
The cowboys in the trade usually run when asked for such written guarantees.

Contact an energy advisor if feeling incompetent to make a decision. He/she might be able to get you a very good deal, safe and reliable. Or they simply shake their head about the energetic situation of your building.

Invest in knowledge first, then you won't have to rely on 'promises'.

Cheers, I think I'm going to have to get a professional (energy advisor) on board to help me choose. If anybody knows anyone like that, please PM me their details.

The plumber I had onsite today said he would put in writing that my esb bill would be below x amount in the first year and under x minus y amount in the second year. I have to say I was happy enough with what he was committing to so maybe I might be safe enough to go down this route. However, I want to pick the right system from the start and not go through the hassle of a potential legal battle if the air source heat pump fails to deliver.

Maybe oil and solar would be an easy out!

Outkast_IRE

jlptheman wrote: »

Thanks for the info, back to the drawing board for me then so!



Cheers, I think I'm going to have to get a professional (energy advisor) on board to help me choose. If anybody knows anyone like that, please PM me their details.

The plumber I had onsite today said he would put in writing that my esb bill would be below x amount in the first year and under x minus y amount in the second year. I have to say I was happy enough with what he was committing to so maybe I might be safe enough to go down this route. However, I want to pick the right system from the start and not go through the hassle of a potential legal battle if the air source heat pump fails to deliver.

Maybe oil and solar would be an easy out!

Im a plumber i have done installs on every type of system many times , and theres one thing thats a fact you cant dispute the best way to heat your home is to ensure as liitle heat as possible escapes, investing in insulation on a new build is the best investment you can make, also ensuring house is as draft free as possible and all window and door seals are working fully.

heinbloed

Jlptheman wrote:

.......my esb bill would be below....

No one can predict future bills, the prices aren't predictable. Even if guaranteed by the supplier - he might go bankrupt.
Did the plumber propably mean kWh of metered electricity usage per year (kWh/a)?

Always ask for the calculation method.

Energy advisors can be found in the yellow/golden pages.

Condenser

jlptheman wrote: »

Hi all,

I'm currently in the middle of a new build (circa 2800sq/ft bungalow with loft conversion) and I had my heart set on trying geothermal plus underfloor heating. I had a plumber/technician onsite today to inspect and it turns out that the soil is too sandy for the ground source heat pump to be effective.

He suggested air source heat pump and he's gonna do me up a qoute for full installation of ashp + ufh. Hes gonna do me another qoute for the same plus hooking up a back boiler in a log burner/stove to assist during the winter.

What should I expect to pay?

Also any tips or advice would be greatly appreciated.

Thanks,
John

John,

the soil is too sandy is the kind of rubbish you hear from installers who do not know about the product they are installing. Sandy soil is no obstacle to a ground source unit. Its only if the ground is excessively dry or too free draining. If the ground is sandy but still moist it can be some of the best ground to install geothermal in because water will freely flow through dispersing energy as it goes. Don't rule out ground source until you look into it a little further

jlptheman

Outkast_IRE wrote: »

Im a plumber i have done installs on every type of system many times , and theres one thing thats a fact you cant dispute the best way to heat your home is to ensure as liitle heat as possible escapes, investing in insulation on a new build is the best investment you can make, also ensuring house is as draft free as possible and all window and door seals are working fully.

Completely agree and will be investing heavily on insulation.. 100mm floor insulation, dry lining exterior walls etc. cheers

heinbloed wrote: »

Jlptheman wrote:

No one can predict future bills, the prices aren't predictable. Even if guaranteed by the supplier - he might go bankrupt.
Did the plumber propably mean kWh of metered electricity usage per year (kWh/a)?

Always ask for the calculation method.

Energy advisors can be found in the yellow/golden pages.

I never asked for anything specific yet, I only asked him would he put in writing the expected performance if I was to use his services. I did use electricity usage as an example. He said he would so I'm happy with that for now. If I am happy with his quote then I will define what exactly I will want a guarantee of.

Condenser wrote: »

John,

the soil is too sandy is the kind of rubbish you hear from installers who do not know about the product they are installing. Sandy soil is no obstacle to a ground source unit. Its only if the ground is excessively dry or too free draining. If the ground is sandy but still moist it can be some of the best ground to install geothermal in because water will freely flow through dispersing energy as it goes. Don't rule out ground source until you look into it a little further

Is this true? I'd still love to avail of geothermal heat but don't want to risk the investment if its not going to be very efficient in the end. I was told that most to least desirable soil types for gshp is: dark dry boggy soil, wet boggy soil, normal dry soil and so on until sandy soil. I may not be remembering that exactly but he said something like that. He also said that sand doesn't hold heat well.

This is a huge decision for me, so much money to invest and so much potential for it all to go wrong! Please help!

Outkast_IRE

So are you Dry lining with insulation inside the house?
On a new build i thought most architects etc would reccomend other solutions to avoid cold bridging etc ?

jlptheman

Yeah dry lining the inside of the exterior walls. I'm not sure on the spec of the insulation I'm using. Whats the problem with doing this?

jlptheman

heinbloed wrote: »

See the previous links about heat pumps.


http://www.waermepumpen-verbrauchsdatenbank.de/index.php?lang=en

heinbloed, I had a look through that link and the average for Air/Water HPs are around 2.5 - 3 CO this year so far. Isnt that pretty good considering an oil burner is around .8?

Outkast_IRE

jlptheman wrote: »

Yeah dry lining the inside of the exterior walls. I'm not sure on the spec of the insulation I'm using. Whats the problem with doing this?

It depends on what way the walls exterior walls are done with regards to cavity and what depth of insulation in the cavity obviously an arctitect would know this sort of stuff in a new build but when fitting it to an old home it leaves cold bridges in spots.
but as i said it mightnt be a issue in your build all depends on what the arhitect allowed for.

Outkast_IRE

jlptheman wrote: »

heinbloed, I had a look through that link and the average for Air/Water HPs are around 2.5 - 3 CO this year so far. Isnt that pretty good considering an oil burner is around .8?

Yeah i see the average is good, but look at the minimum , with the air to water if the winter has really cold air temps the cop goes brutal think about it basically when you need it most it performs the worst.
Also they can end up spending huge amounts of their time defrosting themselves in such cold weather wasting more elec.

The highest efficencies are obviously in the summer which drags the COP average up a huge amount. but in a normal home you wont be using it much during the summer.

heinbloed

The OP asks:

Quote:
Originally Posted by heinbloed
See the previous links about heat pumps.


http://www.waermepumpen-verbrauchsda...ex.php?lang=en


heinbloed, I had a look through that link and the average for Air/Water HPs are around 2.5 - 3 CO this year so far. Isnt that pretty good considering an oil burner is around .8?

No, a COP of 2.5-3 is pretty lousy. Well, a COP of 4 is good, if it contains the DHW as well.

We have to look at the technical side and at the economical side.
Your question was if the HP makes sense in the economical way, if the purchase and running costs justify the choice/preference of it.
So you have to compare the alternatives, a heating engineer and/or an energy advisor would be the ones to ask for help.
You have mentioned an insulation thickness of 100mm in the floor, that's about the minimum legal.
For an UFH you would need more, more like 150mm.
And that is still thin for an UFH, a passive house would propably ask for even more. Gas based insulants will loose their superior thermal insulating effect very quick if exposed to permanently changing temperatures.

About the COP: The COP represents the machine's efficiency at a certain point of meassuring. It does not represent the anual efficiency (or the seasonal efficiency) of the heating system.
If you look at the monetarian issue of your choice of heating system (your question) only a wholesome analysis by the civil engineer, the heating engineer, the architect, the energy advisor will give you an answer.

A HP can be a good choice, even an air-based HP with a low COP. But the parameters have to be met.
If the (external) air temperatures are high and the demand temperature is low (for example in an Irish PH with surface heating, walls and floor) it could be the best economical option.

But then there is still the hot domestic water question. Here a high temperature is demanded, and with a high demand of DHW most HPs come into difficulties with the economics.
Once the structure is well insulated the DHW is the major drawer of energy. And HPs are pretty bad delivering DHW at an economical price.

So you see the situation is complex. Get an energy advisor and/or a proper civil engineer. They propably all would recommend a good thermal insulation, a proper design of the structure. After this it isn't much of an effort to choose the most econonomical heating system.
Once the thermal demand is low (kWh/a and kW/h) anything goes. If you pay lets say €100.-/a more or less this is of little effect on your purse, the overall costs are important. And these include running costs (purchased energy and maintenance) as well as replacement costs.
Don't forget the replacement costs for the energy saving elements. Like Argon/Krypton filled window panes for example.
So get propper advice,pay for it and demand more than ideas but results. And get it in writing!

Good luck!

PS

The solar house concept goes beyond energy saving issues and efficiency of heating systems.It collects all free solar energy, stores it and then it doesn't matter how bad the structure is insulated (well,that's the principle). A free and continously available source of energy doesn't ask for efficiency. Like the trees in the forest, they don't pay and use plenty very inefficiently (smiley).

ciankinsella

Based on my own experience, I think a air to water heat pump is a good investment, provided you also get a backup heat source (for when it's too cold outside for heat pump to work efficiently or sufficiently) such as wood-chip, gas, oil, etc., and decent-sized buffer tank so that you can generate and store as much heat as possible on night-rate.

And ensure you have a sophisticated controller for heat sources, zones, etc.

heinbloed

@ ciankinsella:

In another post you write that you can't controll your heat pump....

See:

http://www.boards.ie/vbulletin/showthread.php?p=72591063#post72591063

Saying:

... I think a air to water heat pump is a good investment, provided ...

is guess work I suppose?

What did the HP cost, how much electric energy hast it consumed and how much usefull thermal energy has it delevired, how old ist resp. how long is it installed now?

Please make a difference between "produced thermal energy" and "used thermal energy". Heating up a storage tank is useless, wasted energy. What counts is what is tapped, used.

And the same for the entire energy system (boiler, HP, solar etc...)

You find all these questions answered in the control units where these data are stored. Would you mind sharing these informations?

Thanks.

ciankinsella

Heinbloed,

1. You have misunderstood what I said in a separate post.

2. Why do you suppose my recommendation is based on guesswork?

I am simply trying to give my view/opinion to the original poster, which is based on actual experience.

Although I'm a layman and you are a professional, I don't really take your point about producing thermal energy that doesn't get used. I have learned a basic fact - that to use my heat pump in its most economic way it needs a decent-sized buffer tank to store heat below 50 degrees. If you're creating heat with burner-type boilers you don't have that limitation and can store more energy in a given amount of water. Although in theory that can lead to some lost energy, in practice it hasn't happened as far as I can see - I installed the biggest buffer tank that would fit in the available space, and indeed it is smaller than optimal. Hence my remark about having a decent-sized buffer tank.

heinbloed

Ciansella wrote:

If you're creating heat with burner-type boilers you don't have that limitation and can store more energy in a given amount of water.

I'm from this planet earth, ciansella. The laws of physics are my limits.
What you have posted is rubbish for me, useless blubber. Talk about gods and saints, miracles, metaphysics....

Who installed that control unit? And why ?

Billy Bunting

ciankinsella wrote: »

Although I'm a layman and you are a professional, .

A professional what ?

30 something

ciankinsella wrote: »

Based on my own experience, I think a air to water heat pump is a good investment, provided you also get a backup heat source (for when it's too cold outside for heat pump to work efficiently or sufficiently) such as wood-chip, gas, oil, etc., and decent-sized buffer tank so that you can generate and store as much heat as possible on night-rate.

And ensure you have a sophisticated controller for heat sources, zones, etc.

Hi ciankinsella, you have a water heat pump and a backup heat source. Can i ask you why you need the back up heat source. Did the system not work properly in the winter and if so is it then not doing the job it's meant to do?
Thanks i am in discussions about buying a air to water heat pump and would like to get your opinion.

heinbloed

I'm joining the queue for this answer.

And I have another question:

How efficient is the heating system/ seasonal efficiency ? Anual efficiency? Is domestic hot water included?

Here is a web page where HP owners/operators can enter their data for everyone to have a look:

http://www.waermepumpen-verbrauchsdatenbank.de/index.php?lang=en

Please enter your data. Don't worry, there are already plenty of investment failures documented by fooled HP operators. And some sucesses as well!

ciankinsella

Hi 30 something,

My situation was that there was already a condensing gas boiler in place, and I wanted to see if I could reduce my bills. My installer recommended keeping this in place and I wanted to do so myself. His reasons were 1) the size of the house (> 500m2) combined with 2) that the heat pump struggles in cold weather.

This is what I have experienced: during very cold weather (which we have had a lot of), the heat pump tends to ice up, and spends a fair bit of time (=money) on a defrost cycle. Maybe it's because we have higher humidity than other countries, maybe it's an issue with the actual heat pump I have, someone more knowledgeable than me might know. Whatever, the result is that in order to keep the house warm, the gas boiler is on as well whenever the outside temperature gets below + 3/4. Just by looking at the pump well iced up, and seeing it struggle to produce water above 40 I would be pretty sure that (certainly at day-time electricity rates) it should be turned off in these conditions in favour of a secondary heat source.

I haven't kept records on the comparative bills and KwH, but on rough calculations I worked out that I spent between 10% to 20% less in the first year on gas and electricity after the upgrade than before, but there were so many other factors (e.g. the winter of 2009/2020 was much colder than the previous one and I had also installed solar panels which work quite well, and a new heat controller) that I really do not know how much the heat pump contributed to this.

I should add that the house did not perform too well in air-tightedness tests, and I did some work on this.