Heat Pumps - post here.

seaniefr

BarneyMc wrote: »

Not sure I follow Seanie. Regarding the floor joists I assume you mean the first floor?

Also are you saying that in some places the floor may be greater than 4"? What's the problem with that - why is 4" the magic number? I'm thinking of using 3".

Also is the sub floor not supposed to act as a heat exchanger/storage medium?

No I mean the ground floor but the method would be the same for first floor.
My architect specified not more than 4" that's all I can tell you. I mean that on the ground floor the floor was raised and joists put in And then battened between, filled with concrete and pipes were immersed in this. Like I said earlier I have seen this done and the homeowner swore by it but that was a couple of years ago don't know what it's like now. The final layer is your storage medium if that's what you mean and that is what I was talking about.

BarneyMc

How would 3" sand/cement work as opposed to 4" with a HP? I assume it would just release the heat a lot sooner?

Condenser

BarneyMc wrote: »

How would 3" sand/cement work as opposed to 4" with a HP? I assume it would just release the heat a lot sooner?

Use a 3" pumped concrete it will give you the best balance between heat retention and reaction time. Much more than this can be difficult to control as you like, much less affects your thermal mass and the HP short cycles.
Heat release depends on the temp above the screed, the closer the two temps the less energy gets released.

seaniefr

BarneyMc wrote: »

How would 3" sand/cement work as opposed to 4" with a HP? I assume it would just release the heat a lot sooner?

Less concrete to heat less to hold hold heat

BarneyMc

Condenser wrote: »

Use a 3" pumped concrete it will give you the best balance between heat retention and reaction time. Much more than this can be difficult to control as you like, much less affects your thermal mass and the HP short cycles.
Heat release depends on the temp above the screed, the closer the two temps the less energy gets released.

This is the answer I hoped for! BUT how did you figure it to be 3"?

sheff the ref

I think people underestimate the exposure to the elements aspect of A2W heatpumps.

Alternatively a GSHP can be nice and snugly fitted into a Garage and well protected at all times.

Condenser wrote: »

Plenty of ground source heat pumps with inverter compressors too but to state that a fixed speed is somehow inferior is nonsense. What "fat old yokes" are you referring to exactly, you're being too technical for me there.
Air to water systems have an inherently shorter lifespan due to a number of factors
Exposure to varying weather conditions repeatedly
Components exposed to extremes of weather (including inverters and compressors)
Cheap units are built with a finite lifetime built in, even the metals in high end units will have noticeable degradation after 10yrs. Cheaper units long before this.
Coil failure due to thermal shock from repeated reverse cycle defrosting
(should I continue)


They are also inherently less efficient
Efficiency drops with outside temp i.e. least efficient when needed most
Icing (a2w units progressively get less efficient from the moment they start to the moment they defrost)
Defrosting, removing energy from the home for no net return
Fan motors, far more energy hungry than circulating pumps
(and the list goes on)


Running costs will depend on the quality of A2W unit so giving you a running cost of an A2W is pointless, but even the best units aren't in the same league as GSHP's and they will cost just as much to buy in the first place. Come back to me when you get those COP stats

Condenser

BarneyMc wrote: »

This is the answer I hoped for! BUT how did you figure it to be 3"?

You get to know what works best down through the years

BarneyMc

Condenser wrote: »

You get to know what works best down through the years

Right answer again!

phobia2011

Are grants still available for installation ?

exaisle

Just to throw a spanner in the works..I have an A2W HP and a Solar Panel. They both have insulated hot water tanks of 180litres and 300litres respectively.
The HP heats the house via UFH and provides hot water for domestic use.
In the winter, water from the solar system preheats water entering the HP.
(In the summer, the HP is switched off and all of the domestic hot water is supplied by the solar system by means of a valve which bypasses the HP).

Ive noticed that even in the winter, when there is a sunny day, it wouldn't be unknown for me to have 300litres of water at 40degrees plus in the solar system....and this evening when I checked, the temperature in the solar tank was 65 degrees.
My question is....is there any reasonably efficient way that I can use this water to heat the water in the UFH loops? There is an unused coil in the tank of the solar system....



E

BryanF

phobia2011 wrote: »

Are grants still available for installation ?

seai.ie

BarneyMc

exaisle wrote: »

Just to throw a spanner in the works..I have an A2W HP and a Solar Panel. They both have insulated hot water tanks of 180litres and 300litres respectively.
The HP heats the house via UFH and provides hot water for domestic use.
In the winter, water from the solar system preheats water entering the HP.
(In the summer, the HP is switched off and all of the domestic hot water is supplied by the solar system by means of a valve which bypasses the HP).

Ive noticed that even in the winter, when there is a sunny day, it wouldn't be unknown for me to have 300litres of water at 40degrees plus in the solar system....and this evening when I checked, the temperature in the solar tank was 65 degrees.
My question is....is there any reasonably efficient way that I can use this water to heat the water in the UFH loops? There is an unused coil in the tank of the solar system....

E

Did you not say in the first paragraph that "In the winter, water from the solar system preheats water entering the HP"?

Cavanjack

BarneyMc wrote: »

How would 3" sand/cement work as opposed to 4" with a HP? I assume it would just release the heat a lot sooner?

Would you not go for the 2" liquid screed barney and have an extra inch or two of insulation in the floor? Will you not have enough thermal mass with your block walls?

Condenser

Cavanjack wrote: »

Would you not go for the 2" liquid screed barney and have an extra inch or two of insulation in the floor? Will you not have enough thermal mass with your block walls?

It affects the reaction time of the heat pump as liquid screeds heat quickly so also cool quickly so you end up with a lot of short cycling of the compressor which is a bad thing and it also will affect temperature control if using weather compensation (which you should be)

BarneyMc

Condenser wrote: »

It affects the reaction time of the heat pump as liquid screeds heat quickly so also cool quickly so you end up with a lot of short cycling of the compressor which is a bad thing and it also will affect temperature control if using weather compensation (which you should be)

ditto!

I may not need more insulation. And sand/cement is cheaper.

I'm hoping the 3" sand/cement would be a good half way house as outlined by condenser above. Also, if I was to ever use PV cells to power my HP I'm hoping the 3" sand/cement again would be a good medium to use rather than the extremes of 2" screed or 4" sand cement. Any thoughts?

planes01

Has anyone here had an issue with limescale build up in the hot water tank?
We have a waterkotte all in 1.
Does anyone know if it's possible to remove or replace the coil?
Thanks

phobia2011

with solar heated cylinder used as a preheated cold supply to heat pump, is there a cycle(hot return) between the two tanks?
what is the best way to pipe this arrangement? is there a schematic anywhere for it?

TIA

exaisle

BarneyMc wrote: »

Did you not say in the first paragraph that "In the winter, water from the solar system preheats water entering the HP"?

Yes, I did.....but this water doesn't find its way into the underfloor system....rather than take cold water from the mains to be heated in the HP for use in showers, the water goes into the solar system first....and even in the winter, every degree that the solar system can heat it before it gets to the HP is a degree that the HP doesn't have to heat.....

Winter: Mains>>>>>Solar tank>>>>>HP tank>>>>>house hot water

Summer: Mains>>>>>Solar tank>>>>>house hot water

Hope this clarifies.

exaisle

phobia2011 wrote: »

with solar heated cylinder used as a preheated cold supply to heat pump, is there a cycle(hot return) between the two tanks?
what is the best way to pipe this arrangement? is there a schematic anywhere for it?

TIA

There's no return to the solar tank from the HP tank. Most of the time the HP tank is hotter than the Solar tank, but the Solar tank is almost always warmer than the mains. Putting in a hot return would be (I think) counterproductive.

I just use a three-way valve to bypass the HP piping:

Winter: Solar

---

HP

---

House

Summer: Solar--@ HP

---

House
.........................|............|
.........................

---

Excuse my awful diagram...please ignore the dots....the valve is at the @ and the minus signs and vertical lines represent the circuit.


My original question was whether it was possible to use water from the Solar Tank, if it's hot enough, to heat the water that's in the underfloor part of the system...

phobia2011

so in summer the hw in heat pump just sits there? and the solar cylinder takes over?

im looking to install something very similar, currently have solar system installed, about to install a nibe 1245, using solar as my preheated cold.
do you have a heat dump on your solar?

exaisle

phobia2011 wrote: »

so in summer the hw in heat pump just sits there? and the solar cylinder takes over?

I'm looking to install something very similar, currently have solar system installed, about to install a nibe 1245, using solar as my preheated cold.
do you have a heat dump on your solar?

No, in the summer, the HP is switched off.

The solar (by Zen Renewables) uses a drain-back system that empties the collector in the event that the tank reaches it's maximum required temperature.

Curious Geroge

Anyone using efergy energy monitor to see the electrical usage of your heat pumps? Would you recommend? Thanks

SOR2010

Curious Geroge wrote: »

Anyone using efergy energy monitor to see the electrical usage of your heat pumps? Would you recommend? Thanks

Hi Curious Yeah I have one, But also have a meter on the HP, Wasn't sure I trusted the efergy but I'll do a few readings over the next couple of days and let you know the accuracy

Bruthal

Energy monitors will tend to over read motor power usage because they don't measure true watts, but only amps. So energy monitors are measuring closer to kva than kw's.

But the ESB meter will only read true watts or kw's , which is lower than simply measuring amps or kva.

Over reading is not too bad in this case though.

hogandrew

Have heat pump costs come down at all? Anyone any idea what a 10kw HP would cost including controls etc. I have a large garden so have the option of geothermal or air to water

Curious Geroge

brianowilliams wrote:

Have had a lot of problems with Nutherm over the last 3 months. Had what at first appeared like a simple problem but their customer service here in galway is very poor. 3 months later and €2000 in costs and system still not fixed.

Curious Geroge wrote: »

Great info to know. I'm about to finalize on a Danfoss unit from heatpumpsireland ....

I posted the above about a year ago, ended up going with the Danfoss unit. I find it only fair to post to others, the HP was ordered and paid for 6 months ago, installed 4 months ago and still no hot water. Would I recommend :mad::mad:

froshtyv

Curious Geroge wrote: »

I posted the above about a year ago, ended up going with the Danfoss unit. I find it only fair to post to others, the HP was ordered and paid for 6 months ago, installed 4 months ago and still no hot water. Would I recommend :mad::mad:

Sorry to hear that, who ended up installing the unit for you?

gunner0098

Hi,

Can anyone PM me a recommendation for a reputable supplier/fitter in the north west?
I have no confidence in my original installer (good sales guy, poor service). I recently contacted another supplier, who came out and reviewed my setup. Appeared sound and knew what they were talking about. Cost me €100 lids for the privilege, which I didn't mind and they were to supply me with a quote for a service and improvement works. That was back in February and nothing since (emails and calls not answered).

catmcgoo

Hi All,

I haven't seen any new threads on this lately. We have just got planning permission granted for a house and we are now looking at heating systems options. has anyone had any experience with an air to water heat pump? Are they cheaper to install than an oil fired central heating. What is the cost to run etc? Any advice would be very grateful!!

BryanF

threads merged