My geothermal heating system experience

I am not disputing the fact that heat pumps can produce heat very cheaply in relation to running costs, my point is that when a house has high insulation levels the resulting cost to heat the house is relatively low.

When this is the case, the installation cost of the heating appliance becomes far more relative.

The installation cost of a heat pump is considerably higher than an oil boiler, possibly resulting in an unrealistic pay back period.

The lower the heating costs, the lower the saving, the longer the relative payback time.

IMO Regardless of the heating appliance there should be no difference in the attention paid to how houses are insulated.
Saying that you need to insulate your house to a higher standard in order to use a heat pump over oil/gas is bull.

Yes if you dont insulate your house to a sufficient standard the heat pump sized for that house wont heat the house or heat it at very high costs, but the same would be the case if you fitted an oil/gas boiler with the same heat output rating. 12-16 kw heat pumps would be a common size where as 26-30 kw is often the oil boiler size fitted in the same size house

Wearb wrote: »

Seeing as the highest demand for heating is in the living area, has anybody ever did regular insulation in the rest of the house, but lots of extra in the living area? It would cut down on insulation costs and also on heating costs. Other areas of the house would be heated to a lower temperature and therefore (heat loss being linked to the temperature difference between heated area and outside) still only the same heat loss as the area with greater insulation and higher temperature.

You'd have to insulate the living area from the rest of the house as heat will flow from the warm areas to the cold and call on your heating more regularly.
Insulate to the extremities of your house and to the best level affordable to you.

None that make any difference to the running cost. You'd actually have to insulate your internal walls and seal off the doors.

Wearb wrote: »

In my house there is a difference. I have the bedrooms on a different zone and a lower temperature. They even feels cooler. Have I wasted my money installing this zone? Common sense tells me that I am making a saving by doing this, but I have no hard evidence.

You're not saving anything as the heat from the warm zones flows towards the colder zones. The warm zones heat constantly and the cold ones rarely switch on as they are satisfied by the warmer areas. The point of insulation is to slow the release of heat from inside to outside by as much as possible. When you have no barrier to heat transfer such as inside then the heat will migrate.

shane0007 wrote: »

This is simply not true. Heat cannot open & close doors after it! By having different zones at differing temperatures is a useful way of saving energy.
For example, bedrooms would be comfortable at a consistent temp of 18c, whilst living areas would be 20c, but bathrooms would be 22c. Why, because of the level of clothing we wear in those rooms, living areas we hopefully wear normally attire, bathrooms we have nothing on & bedrooms we are wrapped up in cosy duvets!
By having the varying temps in each zone, heat loss is based on the outside temp relative to the internal design temp for that zone. We base calculations on -3 outside temp so for a living area that would be a design delta T of 23c but a bathroom would be a delta T of 25c.
With this in mind, each room can be calculated upon its own merits, i.e. u value of walls, floors, ceilings, windows, external doors, etc.
This room having a differing delta T will have a direct impact upon the overall demand of the system & ultimately the running costs of said system.

And what exactly is the u-value of a panel door and the 5-10mm gap underneath it?
Is the door opened at all? Maybe the HRV unit will confine the heat you produce in the living room by sending it back to the living room only?
Bathrooms attached directly to bedroom maintaining a different temp for no extra cost?
Please have a rethink about the situation you suggest as it goes against the laws of thermodynamics. Theres a reason a house is insulated at the extremities.

shane0007 wrote: »

U value of air is 0.025. U value of a timber door will depend upon what material it is made of and then the exact U value can be determined based on its thickness. You could then do a calculation on the size of the wall even down to the 3mm skim coat of plaster U value, work out the size of the door, calculate the delta T between the 22c desired temp of the bathroom & the 18c of the bedroom.
You could further calculate a different U value based upon the door being left open or being left closed.
But then again, that would be just silly now that you have asked me to think about it, which I have and based upon that pondering thought, I deduced that you are still wrong. Furthermore, it still take energy to heat a bedroom from 18c to 22c just because it has an en suite!

Lads, lads, lads has anyone looked at the figures, you can't compare running costs of different systems by saying well my brother used this much oil, etc etc
The bottom line is jp used 3400 units of electricity (I'm not even gonna take the circ pump out of the equation) giving him 20400kwhrs of heating to his house,
To deliver the same amount of heat to his house to heat it to the level he likes it would cost €2422 in LPG and €2040 in fuel oil

TPM wrote: »

Just out of interest what figures are you using to work that out, IMO they seem a bit off?
would 3400 units not realistic give around 15300 kwhrs of heat, costing more like €1530 in oil?

It would with a standard heat pump, but jp did say that the heat pump he fitted was a heliotherm which has a much higher cop of 5.8 at a flow temp of 35 so it's more than likely even higher than a cop of 6 which is what I based my figures on, the fuel oil ang LPG figures were taken from the seai website and I gave the gas boiler an 86% efficiency and 95 for the oil

shane0007 wrote: »

SEAI's figures on LPG are way off the scale. A client of mine just signed a contract with Calor for 63 cent per litre. Nearly all Band A gas boilers are SEDBUK/HARP 90.2%.
The flow temperature you have used is extremely low for UFH. More like 45c.
What water temperature are you achieving for DHW in your calculations?
To bring the water DHW temperature to 55c, I presume it is done by means of a 3kw immersion. Is this cost in your heating calculations or is it thrown into the lighting/socket side of the electricity consumption calculations?

Flow temps in a proper underfloor system shouldn't need to be above 32 degrees unless its below zero outside or your underfloor was fitted by muppets using typical layouts and 150mm or greater spacing and this old craic of one loop per room no matter how big or small it is, also with good weather compensated controls you can limit your flow temps on quite a lot of days throughout the heating season saving you a good of money in the process and improving overall system efficiency,

It is going to be almost impossible to get a direct comparison unless someone decided to install an oil/or gas boiler to heat their efficent house which is currently been heated by a heat pump, even then the comparison isnt realy much use because even though the insulation levels would be constant, heating systems should be designed, installed and "tweeked" according to the specified heat source.

IMO there is no question about the fact that a properly installed heatpump and heating system will heat a house very cheaply.
The question is the feasibility of installing one based on the install costs and payback time of each system.
If the yearly saving equates to a 20 year payback time is it going to make sense

Wearb wrote: »

Originally Posted by Tommyboy08 View Post
Lads, lads, lads has anyone looked at the figures, you can't compare running costs of different systems by saying well my brother used this much oil, etc etc
The bottom line is jp used 3400 units of electricity (I'm not even gonna take the circ pump out of the equation) giving him 20400kwhrs of heating to his house,
To deliver the same amount of heat to his house to heat it to the level he likes it would cost €2422 in LPG and €2040 in fuel oil

---

A point is being left of these equations; 21 degrees all over 24/7 might be practical on the geothermal system, in fact might be necessary giving its response time. On a gas or oil system, the amount of time that it would be heating would be perhaps about a third of that (depending on circumstances). I do understand that the same level of comfort would not be achieved, but those 24/7 temperatures are not necessary for nice comfort. I offer this contribution only to help thread followers, who may be trying to decide on what system to use and comparing one system with the other in this way is a little like comparing apples and oranges.

Well the heat losses on the house are the same no matter what system you use, you can turn down the temp on a heat pump too you know, if that's the temp he wants and I don't blame him, who wants to be getting out of the shower and have to do a dance around the bedroom to keep warm till you get your clothes warm, is that not the point of building houses the way we do nowadays, I remember what it was like growing up seeing the fog coming off your breath in the morning in the bedroom, I'm glad we don't live like that anymore!
Or maybe some of us do?
My point with those calculations was to create that same amount of heat energy would cost that amount with a gas boiler and thems the facts
I was trying to offer those who are deciding on a system the same help, to get themselves out of the dark ages and future proof themselves from the inevitable oil and gas price hikes( and don't start another one of those electricity will rise too debates as we all know it will but very little in comparison) and be able to live in an extremely comfortable house and not have it cost them an arm and a leg every year to run

shane0007 wrote: »

Tommyboy08 wrote: »

Perhaps you could post your information that legionella does not survive at 45c. It can survive upto 55c, not many albeit, but some can. This is the reason regs state 60C to 100% eliminate them. Legionella is similar to asbestos. It only takes one to kill.

With regard to 32c flow rate, could you also post your proof of this as all manufacturers/designers I have come across specify 45C. 32C taking into account system losses will be a lot lower than 32c. Return temps will then be as low as 21c, I would really like to see performance sheets/calculations based upon your set up.

45C flow rates are antiquated and the domain of oil boilers and gas boilers. A properly designed ufh system will rarely top 30C due to higher densities of pipe work and shorter loop lengths. Not one of the 280 heat pumps I have installed would require a flow temp of more than 35. And return temps would not drop as much as you state as the system should be designed with a 5k differential across the loop.

He never stated that legionella does not survive at 45C he merely stated that with a fresh water system he need not exceed it.
Fresh water systems do not need to exceed 45C as the stored heated water never leaves the tank, its merely used to heat fresh cold water instantaneously. The OP discussed all of this and how it works earlier in the thread.

shane0007 wrote: »

When you say a fresh water system, what do you mean exactly by this? A standard domestic hot water cylinder fed by a cwst is a fresh water system. All stored hot water must be brought to 60C at least once a week otherwise legionella can be present. 35C is the ideal temperature for them to multiply, so cylinder stored at 45C will most likely be in the 35c range extremely often as once any hot water is used, it replaced by colder water, thus cooling the system.

The water in the holding tank is heated to 45 degrees, this tank has a stainless steel heat exchanger on the side of it with flow switch and small circulator, when the fresh cold water starts to flow after a hot tap is opened the flow switch turns on the circulating pump and this drives hot water through the heat exchanger to heat the water going to the tap, it is pretty instantaneous and will bring the hot water to one degree of the water in the tank, 44 degree should be well hot enough for any body to wash in.
So no need for costly immersion heaters

TPM wrote: »

I always seem to be over fussy about things like this. Basically if the water isnt moving and between 20-50 oC it will multiply and the longer it is in this state the more it multiplies.

If I understand your system it heats the cold fresh water almost instantaneously and this in turn minimises the volume of water maintained at the temperature and in turn reduces the risk, My concern about this type of design is that in the event bacteria do multiply to high levels the water temperature never gets high enough to kill them off and/or sterilise the pipework and components.

And as always has to be mentioned all components and systems will only do what they are designed to do if they are installed correctly and for some reason this country always seems to have issues in this area with attitudes like "sur it will be alright" "you dont really need to do all that" all too common in the past. although the attitude of doing things right is slowly working its way into the irish mentality recently

German systems, variants of which are installed in millions of homes across europe, so the "sur it will be alright" assumption doesn't stack up. The water isn't stored so theres no issue.

shane0007 wrote: »

In Germany, they have building control. In Germany, they actually check works. In Germany, they have standards that are actually adhered to.



So where does the water in the coil of the cylinder go to if it is not stored? This is a miniature storage cylinder, is it not?

Whats that got to do with anything. The system works the same regardless of what country its installed in.

You've pretty much proven yourself clueless throughout this whole thread so maybe you should go away and educate yourself besides coming on attacking technology in which you're completely out of your depth and tone done the sneering because you have a dislike of the product.