Heat pumps and OPEN VENTED DHW tanks?
I am struggling to find an installer, or manufacturer, who can fit me an ASHP in conjunction with a vented DHW tank. Out here in the wilds of Shropshire, 1000 ft up, the water pressure (or even availability) of mains water is iffy so there are two large cold water tanks in the loft. This also avoids the need for pressure relief to the outside world, in the event the immersion heater decides to boil the tank. Am I chasing unicorn poo, or do such systems exist (even on the Welsh marches)?
I guess I need an MCS installer to avoid planning issues, though I may have those anyway since I have a 20 YO A2A aircon system, and I believe I am only allowed one HP under permitted developments? I do have 10 years of energy consumption data from my oil burner (10 kwhr per day per degree day of heating needs) so maybe I can duck the heat loss calculations?
Absolutely nothing at all to stop any ashp being used with a vented tank except that I'm not sure anyone advertises a vented tank with a large enough coil. Most tank manufacturers will do specials or you can use a plate heat exchanger instead of a coil (arguably better anyway), or just plumb an 'unvented' tank with a vent (although this is unnecessarily expensive). Really this shouldn't be an issue for any half competent plumber.
Doubtless some will give a spiel about legionella, you should run a legionella cycle in accordance with recommendations (although others may argue that this is unnecessary).
Sadly you are getting the usual nonsense of installers who can't think outside their very small box and insist on using the ashp manufacturers pre plumbed cylinder so that they can put complete rookies on the job whilst still charging a premium.
Permitted development applies only to one heat pump so you will need express consent if you already have one. Once you have express consent MCS isn't necessary unless you want the grant. Sadly (and disgracefully imho) MCS is necessary for installation under pd.
You probably can't duck the loss calcs because emitters need to be sized but it might be possible to persuade an installer to use your actual consumption for the system sizing. Most will probably refuse however because as a customer you can't be trusted and likely over-size as a result.
Gledhill do a range of OV HP tanks .. eg Gledhill SL Plus HP 300HP3SQM EE Open Vented - PLUHP300OV, though these are not, of course, part of any manufacturer's standard kit. Sounds like I figured right - I need planning approval for the second HP. Might be easier just to upgrade the existing one and go A2A for the whole bungalow. I used to despise hot air heating, back when it was gas furnaces, but since I want aircon anyway ..
The fact BUS doesn't apply to A2A is another stupid government decision. Much of the continent (well, Scandinavia) runs on A2A as far as I know, thus avoiding a whole ton of freezup issues.
Legionella and even DHW in total are not really a consideration.. I have enough PV and battery to just run an immersion heater on cheap (thanks Octopus) overnight electrons, and leave the heatpump to do the space heating.
As you say though, finding a flexible installer, out here in the wild especially, is a challenge .. much easier to shift BUS-funded boxes en mass. Even Octopus (as Which recommended) won't play with me, whether because they just don't have anyone out here, or whether because of non standard needs, is hard to tell. Maybe they just don't like anyone who has actually done some research. 🙂
Posted by: @dave1234As you say though, finding a flexible installer, out here in the wild especially, is a challenge .. much easier to shift BUS-funded boxes en mass. Even Octopus (as Which recommended) won't play with me, whether because they just don't have anyone out here, or whether because of non standard needs, is hard to tell. Maybe they just don't like anyone who has actually done some research. 🙂
Not sure you are any worse off than those like me who live close to London when it comes to flexible installers. Many including me report similar problems.
Octopus seem to have a fairly good reputation for being tolerably flexible but will only engage if your house fits their current target market.
Few installers, in my experience, like people who have done any research, oresumably because it makes it more difficultf for them to spout bs to get the sale they want. Those that do like such people deserve our custom.
Unfortunately the bus and pd rules, both of which require mcs, have created an industry which some argue is not healthy.
you can use any manufacturers ashp unvented cylinder as an open vented cylinder have done it numerous times as the water flow rate and pressure is quite bad here in the Sw London area! All that the installer needs to do is not use the expansion vessel and combination valve . Cap the prv and plumb it like an open vented cylinder. It’s surprising how many installers don’t know thisPosted by: @dave1234I am struggling to find an installer, or manufacturer, who can fit me an ASHP in conjunction with a vented DHW tank. Out here in the wilds of Shropshire, 1000 ft up, the water pressure (or even availability) of mains water is iffy so there are two large cold water tanks in the loft. This also avoids the need for pressure relief to the outside world, in the event the immersion heater decides to boil the tank. Am I chasing unicorn poo, or do such systems exist (even on the Welsh marches)?
I guess I need an MCS installer to avoid planning issues, though I may have those anyway since I have a 20 YO A2A aircon system, and I believe I am only allowed one HP under permitted developments? I do have 10 years of energy consumption data from my oil burner (10 kwhr per day per degree day of heating needs) so maybe I can duck the heat loss calculations?
- 24 Forums
- 1,416 Topics
- 29.8 K Posts
- 49 Online
- 1,203 Members
Join Us!
Latest Posts
-
RE: Gas Combi to ASHP - Making sense of survey results and proposal.
@irmartini Hello Ian, I wonder if your house is really ...
By JEH , 36 mins ago
-
RE: Advice on potential HW Cylinder size
As Toodles stated, MCS state a minimum capacity of DHW ...
By Derek M , 38 mins ago
-
RE: SCOP and seasonal variations
@derek-m I think a few questions to Homely are in order...
By Toodles , 1 hour ago
-
@hubb84 No experience here I’m afraid, but I think your...
By Toodles , 1 hour ago
-
RE: Samsung ASHP scheduling help
@morh Your post was music to my ears! I am getting a ...
By Elgreco69 , 1 hour ago
-
RE: Issues with Vaillant connectivity via the MyCONNECT gateway
@drew-pa I have given up on the app - right now it is s...
By dr_dongle , 2 hours ago
-
RE: Optimising Energy Efficiency in Rural Aberdeenshire - GSHP vs. ASHP
@transparent Good points! Do you know if because of ...
By bontwoody , 3 hours ago
-
RE: ASHP Advice: High Temperature vs. Low Temperature Heat Pump For Microbore
Hi - we have a Daikin 16kW HT ASHP installed which was ...
By Marzipan71 , 7 hours ago
-
RE: New Fogstar 15.5kWh upright solution
I'm sorry to hear this is the case. This is not th...
By ChickenBig , 10 hours ago
-
RE: Question about Ecodan's Room Autoadapt mode
@gary Thanks. I'm emboldened to give it a go!
By afarmery , 22 hours ago
-
RE: My ASHP is not performing as well as I’d hoped: COP just over 2
@toodles No. But I wasn't forced there either and The K...
By Morgan , 1 day ago
-
RE: Viessmann Vitocal 250-A in the UK
We have a 10Kw Viessmann 200A it SCOP is currently 5.2,...
By MikeF , 1 day ago
-
RE: Jokes and fun posts about heat pumps and renewables
Recent advances in AI are stunning. I enabled 'facial...
By Transparent , 1 day ago
-
RE: Maximising Savings: Navigating My First Year with Octopus Energy and Heat Pump Running Costs
@allyfish Having been on Agile tariff again for several...
By Toodles , 2 days ago
-
RE: Say hello and introduce yourself
@dr_dongle Living as we do on a hill, one side of our p...
By Toodles , 2 days ago
-
RE: Fossil Fuel Fired Heating v Heat Pump?
Another aspect was the DHW heating; the coal fire in th...
By Toodles , 2 days ago
-
In an ideal world a heat pump unit would contain two co...
By Derek M , 3 days ago
-
RE: Installing your own ASHP - DIY
@tomasmcguinness Have you been able to perform any sani...
By IanMK13 , 3 days ago
-
RE: Vaillant Arotherm Settings for New Installation
@drew-pa Ah thanks. Good to know I dont have a misconce...
By bontwoody , 3 days ago
-
RE: Aira Heat Pump: Stylish Scandinavian Heating
On the whole marketing claims vs reality on performance...
By GunboatDiplomat , 3 days ago
Latest Topics
-
Advice on potential HW Cylinder size
By JWilliams89 4 hours ago
-
By Graeme 1 day ago
-
Interesting heat pumps installations
By Mars 4 days ago
-
What is Wrong with our Heat Pump Installation?
By Mars 5 days ago
-
Fossil Fuel Fired Heating v Heat Pump?
By Toodles 5 days ago