Search the Community

Hi All, We are embarking on a self-build and the ASHP was installed yesterday and we are awaiting the commissioning engineer tomorrow to turn on and start heating. I was a little alarmed by the our ASHP supplier planning to just operate the ASHP at its standard operation rather then operating a thermal cycle. From what I have read on line this is important for the concrete screed performance and any floor finishes installed later. I spoke with our tile installer and tile adhesive supplier and they have recommended the following regime which is more or less a 14 day cycle that involves, 5 days of gradual heat increase (2-3C per day) , maintain at expected operating temp for a further 4 days, before a 5 day gradual decrease in temperature. My question is with regard to the expected operating temperature, which I presume is the outflow temperature of the ASHP (45 degree), that the underfloor heating pipework's will be supplying to the screed for these 4 days. My understanding is that the thermostats will be overridden temporarily for the commissioning and the slab will be consistently heated with this 45 degree water - am I correct? If this is so then theoretically will the house be extremely warm for a few days as the slab should come close to the 45 degree temperature?

HI All, i have an LG 14kw ashp powering hot water and central heating in a 5/6 bedroom house approx 350sqm, i have not issues with the hot water side of things, this works perfectly however, the central heating side gives me issues! when the system works well its great and keeps the house warm but at the moment, once or twice a week the buffer tank which is a 50l cordivari version seems to vent all the central heating system pressure out of of the aav at the top. i have changed the valve a couple of times but still have the same issue, anyone have any ideas what the issue/s might be?

We recently had an Aira chap round, (long warranty). Told us a 6kW ASHP would be ok. We're not eligible for a grant because the previous tenant had one installed (even though the grant was £750 over 10 years ago). (We removed the 2012 ASHP—it was a noisy machine, and we’re after something quieter and more efficient - (is this the right thinking?) it's still in the garage). My partner is all for buying new (with a long warranty) I'm up for taking a chance as there's some good value machines out there. - What system would you have if you were to do it again ? Current thinking is 2 zone 60ish m2 under floor heating 16mm pipes 100mm centers + radiators up stairs - aiming to have a low flow temp and take advantage of the thermal mass of the thick walls and floor Looking forward to hearing your thoughts, especially considering the low flow temperature target and potential ASHP options (new vs used) - what should we have on our shopping list - ? Background We bought an old (1850 stone built ) drafty damp house with an ASHP that needed a complete overhaul / insulating / damp problems solving... it's been quite a journey but we now have windows.. so thats nice.. Current Setup Plan: Heating Zones: Ground Floor: ~60 m² underfloor heating with 16mm pipes at 100mm centres. First Floor: Radiators. Aiming for a low flow temperature to maximise efficiency and leverage the thermal mass of thick stone walls and the floor. Heat Loss Calculations: I did some rough heat loss calcs based on U-values from ChangePlan's U-Value Calculator. Heat Loss Breakdown: Area m² U-Value Temp Diff (°C) Heat Loss (W) Extension Walls 44 0.179 25 196.9 Stone Walls 48 1.26 25 1512 Windows & Doors 20.38 0.82 25 417.79 Old Roof 71 0.14 25 248.5 New Roof 34 0.147 25 124.95 Old Floor 56 0.22 25 308 Extension Floor 29.8 0.163 25 121.44 Total Fabric Heat Loss 2929.58 W Ventilation Heat Loss: Volume (m³) ACR Constant Temp Diff (°C) Heat Loss (W) 365.5 1 0.33 25 3025.46 Total Heat Loss (including 20% buffer): Fabric: 2929.58 W Ventilation: 3025.46 W Total: 7364.44 W (7.36 kW)

Anyone using VDI 2035 spec for heating water in an ASHP. Been looking at it seems a smart way to go. No chemicals to turn into a muddy soup, good heat transfer etc. Monitor with a simple conductivity meter and pH meter to control to quality of the water going into and in the heating system By monitoring Conductivity (80 to 1550 microsiemens) Ph 8.2 to 10 And Scale products below 300ppm Any one using are there issues? What if any fitters are you using Do you top up via an Ion exchanger or just tap water (of suitable quality)?

I have an ASHP for heating and hot water. Unless I use the “luxury” DHW setting, my shower mixer adds too much cold water as it requires the thermostatic valve temperature differential to be 12 deg C. Does any one know of a shower mixer that will work with a heat pump hot water cylinder feed, i.e with DHW between say 40 to 45 deg C, rather than at above 50 deg C?

Hi there, I’m quite new to forums but this site looked really interesting so happy to give it a go. I’m particularly interested in hearing about Air to Air ASHPs (or air conditioning units with heat pumps) that could be integrated into the existing ductwork of a 1960s property. It is currently being heated by a 30 year old Warm Air Gas Boiler (Lennox G10) that is still going strong but is probably nearing the end of it’s life and it’s feels like the right time to start considering renewable options. Thanks!

I've recently got quotes for heat pumps, and found one at £4,000 for a Mitsubishi 5/6kw Heat pump, and a 200L cylinder in the loft with 7 radiator upgrades after the gov grant. I'll be adding this onto my remortgage so it's costing a couple of quid a month for the upfront cost. I live in a 2019, 3 bedroomed, small new build so it's very efficient, usually only need the gas combi boiler heating on for 2 hours a day max when it's currently about -1 degrees c. If i get onto the heat pump, I can cap the gas off and stop paying the standing charges for it. I'm currently on Octopus Intelligent with my EV, and I get cheap rates of 7.5p between 23:30 and 05:30, and can get more hours of this within the day when 'charging' my car. Outside of this, it's 30p kw/h. On a usual day, I can get 7.5p kw/h between ; 09:30 - 12:00, 14:00 - 16:00, 20:30 - 22:00, 23:30 - 05:30. My question is, I know heat pumps should be left on 24/7 at a set temperature. However, I could run the heat pump 4x cheaper than the normal electricity rate if I keep within those set times to reduce to 7.5p kw/h. If I set the schedule on the heat pump heating to only run between the above hours, as well as the hot water heating within those times, will it be enough to heat the house? We're comfortable with about 18 degrees, so don't need the house super hot.

Can anyone give me a quick summary, or link, as to the minimum practical external temperature for A2A heat pump installs to function? Background is that I am currently using GFCH underfloor downstairs / rads upstairs, and I have been experimenting with a portable A2A heat pump heater / cooler for about 18 months in the kitchen diner. I am satisfied that it puts off any need for GFCH use by a few weeks either end, a boost to the house via air flow, and gives me a nice cooling facility in high summer. But my unit says it is not practical below 7C external temperature. Were I to look to install A2A units as an eventual replacement for the GFCH would that limit be about the same ie not much use below 7C? Hence my question. Thanks in advance for any replies.

Looking to form a sort of user group for installers and users of RED Heat Pumps with, or without the associated Heatream Hot water cylinder

[Preface: work is about to start in my major renovation project. I am trying to do everything possible to *bring down* costs at this stage. At the same time, I should consider the following question, because it is now or never.] As some people here know, I've bought most of a small house from 1930 (Paris area), and I plan to switch over to a high-temperature heat-pump. The rationale was not having to change the current radiators. Now the contractor (who does have heating as his specialty) is insisting that we do need to do work on the conduits, move some radiators, etc. Hence, I am asking myself whether it wouldn't be better to switch over to low temperature. The architect says that the net cost ( = price of switching the network to low temperature, minus a certain amount coming from the fact that low-temperature heat pumps are lower-cost) would be about 5k eur. (I doubt she's taking into account that, if the network is high-temperature, a smaller hot-water heater is needed; for some reason she has put a 300L heater in the plans.) Is it worth it? The architect seems to be taken aback mostly by the fact that it would be more work for her (but it's not as if I am not paying her enough), and that low-temperature heat pumps take a lot of wall space (I've got only about 1500 books currently, but libraries grow). (For further reference: the previous owners had no problem heating the place with their old gas heater set on "medium" (about 50deg?), even though the place had essentially no insulation. We are installing plenty of insulation, obviously, as some very long threads here attest; thanks to everybody.) (Another factor in favor of low-temperature: the city heat network might reach our block some day (it's 100m away, currently) and joining it might then become possible (though the town says that our co-op is too small for that on its own). That network works only with low-temperature systems.)

Hi, I need some advice on what wet UFH system to get for our renovation of a 1970s 3 bed bungalow. The house had subsidence so in the process of fixing that the floors were dug up and replaced with the following construction: hardcore base, membrane, 150mm insulation, concrete finish. Unfortunately we had no say in this setup so we're stuck with it now. We're left with a 40-50mm gap between the concrete and the base of the front door, which obviously limits what we can do with UFH. There are of course low-profile retrofit UFH options and we'd have liked to have gone with the Nu-Heat LoPro Max with self levelling compound but that is way too expensive for our budget (double what we want to pay). What are our other options, especially considering our 40-50mm gap, and the 150mm insulation beneath the concrete? I've seen the pre-cut boards that pipes are laid in which have no compound/screed on top, would these work well enough with our floor construction? Or should we go down the normal route with pipes in screed but only have 40mm thickness? Insulation below a concrete slab means the concrete becomes a part of the thermal mass, so because it has a slow response time would it make sense for the UFH to be run continuously? We'll be installing an air-source heat pump together with insulation above the ceiling and on the outside of the house with a render and/or cladding, so would this help with the response time and/or be sufficient to run continuously or intermittently? Any help would be really appreciated!

I created a post a few months ago asking people for their thoughts and experiences on heat pumps for a book I was writing and many people kindly replied. The book has finally been published on Amazon and I want to thank all the people who contributed and who I have quoted in the book in Chapter 12. It`s been a while as the illustrations took a long time so I can`t remember which contributors were from this particular group but I know Joe 90, Gone West and Ian R were to name three. If anyone has Kindle Unlimited they can read the book for free at the following link https://www.amazon.co.uk/dp/B09WWBXVD8 The book isn`t just about heat pumps, it covers hydrogen powered boilers, district heating systems, climate change and government responses & legislation, and it is written more from a layman`s point of view than a technical one. Thanks once again to all the contributors here.

I have recently had an LG Therma V monoblock 16KW Heat Pump installed. It has been fitted with a Honeywell T3R thermostat. It appears this thermostat has a cycle 'feature' When the room temperature is within 1.5 degrees of the demanded temperature the thermostat goes into a boiler cycle mode. In this mode it cycles the boiler on and off a preset number of times per hour. When installed, the setting was 6 which means the boiler is on for 5 mins then off for 5 mins (6 times/hour) On this heat pump this serves no purpose as the pump takes more than 5 mins to start hence power is wasted while running the circulating pump to no effect. If the thermostat cycle time is set to 1, as described in the installation booklet, then the boiler is on for 30 mins and off for 30. This at least allows the heat pump to start and run but due to the slow warm up has little effect before it is switched off again. I can see the cycle time might work for a gas or oil boiler to maintain a background heat level, but with a heat pump all it seems to do is waste energy! When the room temperature is more than 1.5 degrees below the demanded temperature the thermostat switches on in the normal manner until the demanded temperature - 1.5 degrees is achieved. In practice this means that the thermostat temperature has to be set 1.5 degrees above that desired as the cycling of the thermostat largely achieves nothing except wasting energy. Has anybody any suggestions for a 'non cycling' programmable wireless thermostat or will the HP accept a modulating thermostat?

How important is the annual maintenance service and what’s involved in it? Right now, it looks no different than the annual boiler service. This is what I have · Clean evaporator coil; · Check antifreeze; · Clean magnetic filters/strainers; · Remove trapped air; · Check primary pressure; · Check flow rate; · Check controller settings; · Ensure heat pump system is safe; · Clear debris from drip tray and ensure water is draining away correctly;

Hi there Just starting out on a house build and find there are A LOT of decisions. Planning permission has been granted but that's as far as I am. I would appreciate some thoughts on heating systems. Plan is a high level of insulation (eg CWI: 150mm thick Kingspan Eco Bead / Quinn lite block, Floor: 100mm foil backed polystyrene) , triple glazing (uPVC frame) UFH for downstairs and radiators upstairs. I've considered Heat Pumps but I am being recommended OFCH - specifically Grant Vortex. In looking at this option I came across Hybrids and wondered if anyone had experience of this: Grant VortexAir Range: https://www.grantuk.com/products/hybrids/? I live in NI so there are no grants available to apply for... Any advice appreciate Meabh

Hello - I am renovating a house and facilities for myself and family. I am not a heating engineer. There is a 25kW air to water vertical standing heat pump ( no brandname). It heats a 14k gallon swimming pool. The fan on the top has broken. It appeared to be blowing air out vertically when it was operating. I don't know if the replacement fan should be a suck or blow fan? I believe that air will move up inside the heat pump travel over the motor, then to the fan and then out of the top of the unit, so I believe the fan will be a blow orientation. Before I make an expensive mistake, I wondered if anyone could advise me?? Hopefully if I get it wring there will be no damage. Many thanks Brian

Starting to look at air to water heat pump options but I don't want RHI and ideally I'd like to self install. Has anyone bought a new product direct and could recommend a supplier? I'm in Cornwall if it helps. I'm also doing the usual eBay browsing. Many thanks

About ready to lay my screed. Worked out heating requirements and pipe spacing. Pipe and 6 point manifold ordered from Wunda - 3 loops in the same room, very similar lengths being run as one zone so nice and simple (hopefully!). When I spoke to Wunda prior to ordering they mentioned not ordering one of their complete kits as the pump / mixer arrangement isn't ideal for a heat pump. The bloke did try to explain but to be honest I didn't fully understand and at this point really just want to get the floor down. Is there anything else I need to consider at this stage or can I figure the rest out as and when a heat pump is purchased? Does anyone have a quick explanation for an UFH luddite about the mixer /pump issue? I've searched site and previously found reference to something similar but can't find again annoyingly.. System is likely to be heat pump serving UFH and DHW with UVC. Many thanks