Heat Pumps - post here.

deezell

https://www.boards.ie/discussion/comment/121167860#Comment_121167860

1500 l buffer tank about €1500, stores 60kwh from 20kwh heatpump consumption. Tank will last about 50 years.

25kwh of solar batteries about €10,000, after charge discharge/inverter losses, usable output about 20kwh to the heatpump. Batteries will decline rapidly after ten years.

graememk

https://www.boards.ie/discussion/comment/121167982#Comment_121167982

Flip where you buying your buffer tanks, that's a steal(also huge) also 50 yrs will be a push, 20 is a push!

28kwh+ change of batteries for under 5k.

I'd expect still to have 80% capacity after10 yrs easy, it's a linear loss, it just doesn't fall off a cliff.

https://www.fogstar.co.uk/collections/seplos-mason-kits/products/seplos-mason-280l-and-x16-grade-b-envision-305ah-battery-bundle

Mr Q

https://www.boards.ie/discussion/comment/121167982#Comment_121167982

Your prices are off on the batteries, I wouldn't know on the buffer tank what they cost.

Batteries are still the better option in my view. You can't use the buffer tank for any other purpose. The batteries will run house and HP on night rate.

MacDanger

Hi

We're building a new house and looking at heat pumps at the moment - what size of water tank would people recommend? Is a 200L tank enough? 4 people in the house

Thanks

HotSwap

https://www.boards.ie/discussion/comment/121168571#Comment_121168571

I just got a new 180L unvented Kingspan ultra steel two weeks ago. It’s a great tank for my needs 2-3 showers per day and a bath for the baby.

we use about 450 L of water per day on average. This is both hot and cold water.

We definitely don’t use a full tank of hot water per day; but you can always heat it up multiple times per day.

make sure you get something like the ultra steel with the immersion and coil down the bottom of the tank.

MacDanger

Hi

I've another question in relation to heatpumps - how many zones/stats would you expect in a 215m2 house? Is 2 enough? Or would you want more?

Thanks

graememk

https://www.boards.ie/discussion/comment/121169637#Comment_121169637

are you going under floor or radiators? (new house so id guess uderfloor)?

MacDanger

https://www.boards.ie/discussion/comment/121169717#Comment_121169717

Yeah, ufh upstairs and downstairs

graememk

https://www.boards.ie/discussion/comment/121169737#Comment_121169737

You are likely to have multiple loops per floor but likely one zone for upstairs and one for down.

or even no zones at all!

MacDanger

https://www.boards.ie/discussion/comment/121169760#Comment_121169760

Sound, thanks 👍

MacDanger

https://www.boards.ie/discussion/comment/121169760#Comment_121169760

Follow up question - the reason I ask is that one quote we got has two stats while the other one has 7 stats. Is there a reason for one approach vs the other? I had presumed that 7 would be better but from your reply, it doesn't seem to matter

graememk

https://www.boards.ie/discussion/comment/121169980#Comment_121169980

It's complicated, but zoning off can reduce efficiency by increasing the return temperature of the system

Some watching.

https://youtu.be/zpTVIeUh04E?si=-D14HZLr7hsskDgn

https://youtu.be/4J_c-s1BSUU?si=C4QVFTwVBnLYx7jv

ECO_Mental

https://www.boards.ie/discussion/comment/121169637#Comment_121169637

I have 12.....every room is its own zone and corridors. Is it overkill, I don't think so. Mine is a 220m2 one off new build. All underfloor upstairs and downstairs.

I set and forget them. Let's people decide what they want.

ColemanY2K

https://www.boards.ie/discussion/comment/121170802#Comment_121170802

I'm similar, 8 stats/zones across a 193m2 bungalow.

180 litre tank in a 4 bed house. 2 adults and a baby. Not moved in yet but plumber recommended the tank. I'll ring his neck if it isn't big enough lol.

HotSwap

https://www.boards.ie/discussion/comment/121171161#Comment_121171161

Just max out the available space. Get a slimline tank of you have height but not depth. The next size up was 210L; which I could have fit in; but we would have needed to put the expansion tank somewhere else. I’d say go for 210L if you can fit it. It’s only a few extra euro and you won’t regret it

KCross

https://www.boards.ie/discussion/comment/121171161#Comment_121171161

Whether 180l is enough or not will be entirely down to how long your showers are and also how big your family is going to grow.

180l wouldn't do us... 5 people and power showers and it can get through that water quickly. We've a 300l tank.

newhouse87

https://www.boards.ie/discussion/comment/121170802#Comment_121170802

Have 7 stats and 17loops but for this winter i have opened all zones to run off the 1 programmable stat i have. Meant to be more efficient to have them open but time will tell. Have 242sqm new bungalow. Gonna try running on lowest lwt i can find to get me to 22deg in the house and run from 5am to 9pm. Fan bit noisy for my liking in depths of winter to run during the night.

HotSwap

https://www.boards.ie/discussion/comment/121171560#Comment_121171560

There was something about going too low on the lwt on one of the heat geek videos recently I think. If I find it I’ll send it on.

At some point it’s going to come down to comfort Vs efficiency; I’ve just one zone valve for all the heating (rads up and down) but then I have a TADO on each rad. I really like the ability to have different rooms at different temps. I’d happily trade off a few points on my COP for this flexibility.

I’m still using oil; so it’s not as critical for me. What do other people think of this?

deezell

Zoning is not the magic bullet people think. Individual room zoning is only partially effective if heat can move easily through party walls and open doors. Spring loaded doors as fitted to new builds to massage the Ber to an A would test the patience of a Saint, and the constant slamming would drive you demented, particularly in semi detached new builds.

Regardless of whether you use oil, gas or heatpump, the source doesn't know how much demand is being made on it, one room or whole house. The use of smart thermostats will however enable better control of source supply, as such stats will learn the response to a call for heat, and manage the firing of the source in modulated bursts to gently approach target temperature. Similarly the thermostat will predict the rate of fall, and introduce small bursts of heat, enough to maintain the required temperature. I can see these bursts on my stat log, they often take place before the temperature has fallen past set point, and are of very short duration. This not only means a very steady room temperature without over and undershoot, but also aids efficiency, as the short bursts mean that flow return is generally low temperature for most of the bursts, aiding the oil boiler condenser to recover heat. Due to the lower temperature swing available in heat pumps as a source, and the longer response times of ufh, this may not be as effective with a heat pump source. In a steady temperature period however, a smart modulating thermostat would be an asset to assist in more efficient operation of the heat pump, and zoning could be confined to perhaps no more than three or four areas or groups of rooms. Its a fallacy though to think that heating everywhere at maximum heat pump efficiency is less costly than heating just one zone, even with perhaps a period of less efficient heat pump COP.

newhouse87

https://www.boards.ie/discussion/comment/121171645#Comment_121171645

Think if you go too low it may cause pump cycling. I wont be going that low just lowest that i can get house to 22 as last winter the way installer had it setup was stat would call for heat in a room, pump will throw out high temp lwt (using weather compensation curve that was set too high as installers dont take the time to get these important things right and most homeowners never question things) until room hit setpoint, then go off, then another stat may call for heat an hour or 2 later and heat pump would again have to get up to high temp lwt to heat that zone, slow and steady is meant to be the way to go. 22 is bit warm for bedrooms so will adjust flow meters to lower them a bit to give maybe 20 in bedrooms. All ufh i have.

Great website

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/

newhouse87

https://www.boards.ie/discussion/comment/121171669#Comment_121171669

Dunno man, heat geek among many other sources reckon steady low temp flow constantly is more cost effective then a heat pump switch off and on by stats and having to repeatedly get up to a higher temp to get different rooms to their setpoints.

deezell

That's the principle of modulation, and also the basis of opentherm boiler interaction with the thermostat. Once target is achieved, you reduce to source temperature so that a constant flow is required to maintain heat. This would mean that the circulation pump is almost running constantly, but the heat source is operating at reduced temperature, which is achieved by modulation, turning the source on and off in short bursts.

Most existing oil and gas installs will not have the facility to quell the boiler while the pump is running though, the nearest to this you can achieve is to cap the actual boiler temperature itself to a low level, so that firing stops even though target room temperature hasn't been reached, but circulation of this lower temperature flow continues. The problem is that it can take too long for a cold zone to heat up from a standing start, a bedroom say which is off until 7.00. During a cold snap rooms may never reach target, as the output of the rads are too low with this capped flow temperature. This by design is not a concern if you choose UFH, you are effectively committed to maintaining a near comfortable temperature, as instant response to heat a frigid room, especially with low UFH temperatures limited, is not really an option. UFH combined with Heatpumps is probably ideal, the lower temperature of heat pump flow best suits UFH which will further reduce the flow temperature with its own mixing valves, blending flow and return to limit for temperature and prevent burnt feet.

I must research heatpumps to see if any of them are compatible with Opentherm thermostats, whereby the stat can interact directly with the heat source and control its temperature. It's mostly confined to gas boilers afaik, and doesn't generally support active zoning, just passive zoning.

newhouse87

https://www.boards.ie/discussion/comment/121172010#Comment_121172010

Yeah its ufh i'm essentially talking about.

graememk

https://www.boards.ie/discussion/comment/121171645#Comment_121171645

Have a tado on each rad here, and its quite bursty, especially with low heat demands, and the UK version now has removed all the openthem stuff/smart communication with boilers. wouldnt really play nice with call for heat for heatpumps. Athough if the call for heat was via another device that could be a different story.

My house yesterday, at 5 the call for heat kicks in to bring the room up to 20c as its set on the schedule, the Tado valve opens, but you can see it pulsing the heat from my buffer tank. (500L). I Mix down the buffer tank temperature to 45 as an experiment last year. but you can see it start and stop.

It Nearly reached the temperature before the buffer tank ran out of power. (heated from excess solar currently)

Last year it was heated from immersions, this year is going to be heated from a heatpump when i get it in. Plan is to set a pretty large delta so when the heatpump kicks in it will have about 10kwh of heat to bring the tank back up to temperature. thus longer run times.

HotSwap

https://www.boards.ie/discussion/comment/121172350#Comment_121172350

You can still order the opentherm version on the tado website I believe. They did an interview with heat geek about a year ago where he grilled them. I have an oil boiler that dosent support open therm anyway so it’s wasted on me.

so is the buffer also heated by a boiler? Or it’s basically in line with the heating loop?

how do you prevent the heating from being depleted into the buffer when it’s cold? Or is that the point?

graememk

Immersions! It's a 500L direct stainless steel tank. Basically an electric boiler right now.

Last winter I heated it from cheap night rate electric ( was cheaper than oil)

Rest of the heating of the house was by turf in a stove.

The tank could give the morning boost and depending on how good the day was an evening one.

In the middle of winter the stove never went out, was kept ticking over all day, cleaned out and fired up for the evening.

I have configured it so when the house no longer needs heat the stove will then heat the buffer tank.

Haven't had oil since march 2022.

There is a thermostat at the top of the tank that will cut off the pump when it gets cold.

poker--addict

To add to the COP debate. Unfortunately there is also an Oireachtas report suggesting 50% of heat pump installs are being done sub-optimally, in Ireland. Translated that means the pumps are working but costing more money and energy than they should to run, hindering the states carbon targets. It's an appalling statistic but unsurprising- as almost any of the gurus you can follow on the subject all talk about the importance of install over many other factors the uninformed would might rank as being more important.

deezell

https://www.boards.ie/discussion/comment/121174023#Comment_121174023

This was always going to happen, when the exaggerated, misleading information and downright falsehoods on renwables, solar, EVs and heatpumps was being lapped up by fanatical green supporters who were being told what they wanted to hear, and not the hard facts.

Here's a modest Dutch approach to heat pumps as a hybrid alternative or assistant to your current heating system rather than an outright replacement. The 'Vincent' unit, fitted indoors, is €4000 ex vat. It has a nominal output of 4.25 kw from an input of 1.7kw. COP is realistically stated as 2.5. It has the form factor of a largish wall unit or an under counter appliance. It is connected across your existing flow and return, and can operate as your sole heat source, or can transfer to your existing burner if it runs out of steam, or if your home needs more than 4.5 kw to maintain comfort. Ideal for a well insulated terrace house or modern semi. Installation is simpler than a replacement gas boiler, two water pipes and plastic air pipes and as a bonus, it can be hooked up to your central ventilation system as fitted in new homes, to extract a higher COP by scavenging the heat from the stale air.

I can imagine the reaction of the Dutch if you told them to remove their small gas boilers, which they sparingly use, and replace them with the monstrously expensive heat pump installs being peddled here. This is a realistic and ideal solution for inexpensive retrofit, and a big but affordable step towards less dependency on fossil. Watch the YouTube, turn on CC and Auto translate.

https://youtu.be/kcNbjn5XLss?si=caqcNJz0Kre2QNAX

.

HotSwap

https://www.boards.ie/discussion/comment/121174023#Comment_121174023

Part of the problem is peoples total inability to think about heating in terms of comfort and room temperature rather than times and hot hot radiators feel.

This forces plumbers to make decisions that match system performance to the perception of the end users.

Ive attempted to help some friends set up their heating systems in a similarly efficient manner as my own; but it was like hitting my head against a wall; so I’ll never be volunteering my help again. I can see why plumbers do what they do.

Part of the SEAI grant should be a 1 year review of the COP to ensure it’s as good as it can be.

poker--addict

I think that is a cop out my plumbers tbh, no pun intended. If it's explained right, and people are told not to touch it, and it works right, then why would anyone question it? Low slow heat in a home is far more comfortable. I acknowledge you have experience trying to help others and have seen it differently. I know most of my peers say they "don't touch it at all". In my opinion people end up playing with it in most cases bcz it's not setup right, if it's setup right it will compensate right.