Why do we need pressurised systems?
Having had a second occasion where the system pressure for the heat pump dropped to zero (under investigation at present) I go to wondering:
Why do we need a pressurised system in the first place? I have always assumed that a positive pressure is used to ensure a constant supply of water to the pump(s) thus reducing air bubbles which would be purged from the system during circulation and possibly also to avoid risk of cavitation in the pump impellers.
Have I summed it up correctly or am I nowhere near the truth - is there something else I have not thought of perhaps?
Curious Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
@iaack I enquired of Wattson and the reply was very much along the lines of that which I surmised Holmes.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
Posted by: @toodles@iaack I enquired of Wattson and the reply was very much along the lines of that which I surmised Holmes.
@toodles Is that because the AI has searched the forum for information, and has found and paraphrased your own question and assumptive reply back to you, reinforcing your own assumptions (which may well be correct). Just surmising 🤣
Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 7.2kWp solar (south facing), Tesla PW3 (13.5kW)
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.
@old_scientist If that were the case (and it might well be the case I suppose!) perhaps Wattson would be a bestie to a certain President 😉. Oops, Sorry! No Polyticking! Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
A good question @toodles. My old open thermal store and oil boiler chugged away quite happily, if expensively, unpressurised. But the header tank was sat right on top of the thermal store in the airing cupboard, with stagnant water sitting at a cosy 30-35degC breeding and growing all manner of questionable organic produce inside it. 🤢
Pressurisation and sealed systems eliminates the crusty & stinky stagnant header tank issue, and almost completely eliminates risk of pump cavitation. There's a net positive pressure at the pump suction inlet far higher than the minimum the pump requires, and at all points in the pipework system for that matter, making pump or system cavitation anathema. So it doesn't really then matter where in a sealed system the circuit the primary and any secondary pump are placed - they'll do what they do, pumping water. It also usually means a quieter running system with less air entrainment & gurgling.
A sealed system eliminates many corrosion risks. Air in systems promotes internal corrosion. Corrosion needs an oxygenated environment to thrive. No air = no corrosion, theoretically.
And yet installers still do strange things, such as fitting auto air valves on sealed pressurised systems. Open system + auto-vent - yes. But sealed system + auto-vent, er, why? Over time the vent will open, and pressure will be lost. I much prefer a manual air vent, which I can open up to let air escape and then check the system pressure on the gauge and top up slightly with the filling loop if need be. A month or two after system filling no more air separates out and, provided the system is holding pressure, the manual vent never needs checking.
- 26 Forums
- 2,136 Topics
- 46.8 K Posts
- 29 Online
- 5,662 Members
Join Us!
Podcast Picks
Latest Posts
-
RE: Powerwall 3 or Myenergi or something else?
We have a Tesla Powerwall 3, recently installed, so I m...
By Old_Scientist , 6 hours ago
-
@majordennisbloodnok The drying out of air shouldn't ha...
By dgclimatecontrol , 7 hours ago
-
RE: Does anyone have experience of a smart water meter?
Thanks, @technogeek. So far as I can make out, whilst...
By Majordennisbloodnok , 1 day ago
-
RE: Mitsubishi PAR-WT60R-E Wireless Controller installation
@morgan They have been paired once but it was thought b...
By DavidAlgarve , 1 day ago
-
RE: Isolating the system for a planned power cut
A great many ground-mounted local substation transforme...
By Transparent , 1 day ago
-
@bontwoody From what I’ve learned the hard way: 1) T...
By DREI , 2 days ago
-
RE: Heat Pump Servicing & Maintenance – Good Value or Rip-Off?
Having bit the bullet and paid £250 for a service, our ...
By Old_Scientist , 2 days ago
-
New heat pump heating system underperforming in Italy... Advice needed!
hi all, first post! I've just renovated a house in sout...
By robinlawrie , 2 days ago
-
RE: Anyone still weathering it out with Agile?
I went to Agile when I had solar installed July last ye...
By NJT , 3 days ago
-
RE: Mitsu Wireless Controller and MelCloud
Well it has now become obvious that the installation of...
By DavidAlgarve , 3 days ago
-
RE: Say hello and introduce yourself
Whilst you're busy installing services (pipes and wires...
By Transparent , 4 days ago
-
RE: New Vaillant aroTherm Plus in black - When will it come to the UK?
@editor I know it was formally announced at Ish the oth...
By PatrickVito , 5 days ago
-
@moman0311 welcome to the forums. I've received your em...
By Mars , 5 days ago
-
RE: Thermostat for Ideal Logic Air with 3 zone support
No harm at all in plumbing it as 3 zones, I would have ...
By JamesPa , 6 days ago
-
RE: ASHP heat output monitoring
@carlo I see there is a discussion in Facebook user gro...
By Tim441 , 6 days ago
-
RE: Flexi-Orb Heat Pump Scheme: A Game-Changer for the UK's Heat Pump Industry
MCS have set a potential trap in the new version of MCS...
By JamesPa , 1 week ago
-
RE: Who has a V2G EV installation
General comment on battery care... I guess if ev is on ...
By Tim441 , 1 week ago
-
@old_scientist like for like comparisons are almost imp...
By Tim441 , 1 week ago
-
RE: Who's your electricity provider and what's your tariff?
@old_scientist There is an option in the Tesla app that...
By Toodles , 1 week ago
-
RE: Octopus Cosy & Octopus EV + bidirectional smart tariff, together. What, eh?
@old_scientist me too. Just installed my new heat pump ...
By Eliuccio , 1 week ago