Hire the best Air conditioning and Heating Experts

hydronic radiator panels connected to heat pump?

Results 1 to 13 of 13
  1. #1
    Senior Member ForeverYoung's Avatar
    Join Date
    Jun 2021
    Location
    Perth Hills WA
    Posts
    268

    Question hydronic radiator panels connected to heat pump?

    Early days of research.

    TLDR: Can I connect panel radiators to a heat pump that is also used for HW?

    Perth isn't known for having a cold problem like Tassie or Melb or ?
    But where I am in the Perth Hills it is pretty cold in winter.

    Long story short before next winter I am looking to improve my HWS and it sounds like a heat pump is the go. (My solar HWS is ok outside of winter but too shaded to be of use and the booster is uneconomic). I will probably keep the Solar HWS as it is near the laundry (with a shower) and not too far from the kitchen.
    There are 2 ensuites on the other side of the house (1 upstairs, 1 down) and it seems logical to put the heat pump there. Short run plumb to existing pipework.

    I am also think of putting in hydronic radiator panels in 2 of the downstairs rooms, the locations would be almost next to the heat pump. The other downstairs rooms are heated by a woodfire or a rev AC.
    I could even put a panel upstairs, but not really a need.

    So, research doesn't really throw up panel heaters hooked into heat pumps that are also used for domestic hot water usage.
    Looking at the WA websites that mention hydronic they all seem stuck on gas boilers.
    And looking at other websites I haven't seen it specifically mentioned.

    In my simplistic thinking I am seeing the panel radiators as just an extension to the heat pump tank.
    Or in a split system the heat pump heats the radiators and the separate HW tank?

    Anyone done this?

  2. #2
    Senior Member
    Join Date
    Aug 2020
    Location
    Melbourne
    Posts
    120

    Default

    I thought I remembered seeing combined systems similar to what you are describing, but after a quick search I'm not coming up with anything either. And when I think about it, I'm not sure it makes that much sense. For one thing, the two systems have different requirements: the hot water tank needs to have the water around 60C at all times so it is ready on demand. Whereas the heating system only needs to heat and pump the water when the home thermostat turns it on at the set room temperature. If you pumped the hot water system water through the hydronic panels all the time, the house would be too hot. I guess maybe you could switch a valve and pump to pull water from the hot water heater, but it just doesn't seem like anyone does this. Hydronic water may need to be heated higher to be effective.

    When replacing the gas boiler for my hydronic system last year, I considered using a heat pump system instead. But the unit cost was going to be about 3x the price of the gas boiler. I don't have solar yet, so I just couldn't justify the cost at that time. For a smaller system like you are describing, in a place where you may also use it less over the year, I would think the financial payback time could be many years. If you just want to reduce your gas usage though, go for it!
    Owen in Melbourne

  3. #3
    Senior Member
    Join Date
    Aug 2020
    Location
    Melbourne
    Posts
    120

    Default

    Oh also, I found this article: https://renew.org.au/renew-magazine/...ronic-heating/

    These folks undertook a big energy system upgrade on their home, but they installed separate heat pumps for the hydronic vs the hot water. You would think if a combined system had been available, they would have used it when replacing both the water heater and hydronic boiler.
    Owen in Melbourne

  4. #4
    Senior Member ForeverYoung's Avatar
    Join Date
    Jun 2021
    Location
    Perth Hills WA
    Posts
    268

    Default

    Quote Originally Posted by autojack View Post
    I thought I remembered seeing combined systems similar to what you are describing, but after a quick search I'm not coming up with anything either. And when I think about it, I'm not sure it makes that much sense. For one thing, the two systems have different requirements: the hot water tank needs to have the water around 60C at all times so it is ready on demand. Whereas the heating system only needs to heat and pump the water when the home thermostat turns it on at the set room temperature. If you pumped the hot water system water through the hydronic panels all the time, the house would be too hot. I guess maybe you could switch a valve and pump to pull water from the hot water heater, but it just doesn't seem like anyone does this. Hydronic water may need to be heated higher to be effective.

    When replacing the gas boiler for my hydronic system last year, I considered using a heat pump system instead. But the unit cost was going to be about 3x the price of the gas boiler. I don't have solar yet, so I just couldn't justify the cost at that time. For a smaller system like you are describing, in a place where you may also use it less over the year, I would think the financial payback time could be many years. If you just want to reduce your gas usage though, go for it!
    Thanks for the thinking.
    Yes, you are probably right in your conclusion but I am still unclear as to the reasons. I might try and hone in on a Perth hydronic specialist next week to find out.
    My only experience with radiator panels has been in Europe as a user and I seem to remember each room panel could be controlled individually - on/off and a vague temp setting (which seemed to control the water volume more than anything else?). Not sure what happened at the boiler end if all of them were turned off?

    Gas isn't an option here as it would be bottle gas and is too expensive for HW. Otherwise I would just whack an instantaneous gas HW on the ensuites (I am a big fan of them). Tho once I get the heat pumps quotes gas might seem cheap

    A 2nd solar HWS isn't an option - too shaded.
    So it has to be an efficient electric hence heat pump conclusion for HW.
    Just hoping I can piggy back some panels heaters off it.

    The house has 2 PV systems - one on a shed and one on the house. 2 inverters. So outside of winter when the sun is higher (less shade) those do help with my grid consumption.

    Quote Originally Posted by autojack View Post
    Oh also, I found this article: https://renew.org.au/renew-magazine/...ronic-heating/

    These folks undertook a big energy system upgrade on their home, but they installed separate heat pumps for the hydronic vs the hot water. You would think if a combined system had been available, they would have used it when replacing both the water heater and hydronic boiler.
    I will have a read when I get some more time. I always find the Renew stuff a rabbit hole

  5. #5
    Senior Member
    Join Date
    Aug 2020
    Location
    Melbourne
    Posts
    120

    Default

    What you are describing in Europe sounds like a thermostatic valve on each panel. I've mainly seen those in apartment buildings that have central heat and no thermostats in the units/rooms. The boiler runs on a schedule outside of your control, and the thermostatic valve adjusts the rate of water flow through individual panels. If all valves are close, the boiler still runs, it just pumps water through the bypass loops and not into the panels. So getting back to what you are asking about, there would need to be an in-house thermostat of some kind to control the flow of water to the panels. That would need to control a valve and pump somehow attached to the hot water heater - not standard components of a HWS.

    This combined unit seems like it might do what you are talking about: https://www.hydrosol.com.au/heating-...ing-hot-water/ But the fact that research doesn't turn up anything else like this makes me skeptical

    To me it seems like you will have an easier time installing separate split AC units for the heating/cooling, and a heat pump water heater on its own.
    Owen in Melbourne

  6. #6
    Senior Member ForeverYoung's Avatar
    Join Date
    Jun 2021
    Location
    Perth Hills WA
    Posts
    268

    Default

    Quote Originally Posted by autojack View Post
    What you are describing in Europe sounds like a thermostatic valve on each panel. I've mainly seen those in apartment buildings that have central heat and no thermostats in the units/rooms. The boiler runs on a schedule outside of your control, and the thermostatic valve adjusts the rate of water flow through individual panels. If all valves are close, the boiler still runs, it just pumps water through the bypass loops and not into the panels. So getting back to what you are asking about, there would need to be an in-house thermostat of some kind to control the flow of water to the panels. That would need to control a valve and pump somehow attached to the hot water heater - not standard components of a HWS.

    This combined unit seems like it might do what you are talking about: https://www.hydrosol.com.au/heating-...ing-hot-water/ But the fact that research doesn't turn up anything else like this makes me skeptical
    Yes, you are right to be skeptical.
    My superficial thinking and research on it agrees - sounds like the pumping required to get it to the panels might be the issue?

    from that article:
    Choose a hydronic heat pump instead of a gas boiler if you want integrated heating, cooling and hot water. ...
    Keep in mind that your heat pump can only perform one task at a time so if you are using it for both heating, cooling and/or pool heating, it is better to have a separate hot water heat pump.
    Quote Originally Posted by autojack
    To me it seems like you will have an easier time installing separate split AC units for the heating/cooling, and a heat pump water heater on its own.
    None of the downstairs needed cooling last summer (my 1st in this house) - and that is saying something with Perth summers.
    I am only thinking of 2 rooms downstairs for the panel heaters - a bedroom that has the ensuite and a small lounge (none of these are in use as yet as they are being used for storage so I don't have personal experience of living in them as yet).

    HW is the main issue. Total cost of ownership over 5/10 years would be an interesting exercise for a heat pump. The cheaper ones have a lousy warranty.

  7. #7
    Senior Member
    Join Date
    Aug 2020
    Location
    Melbourne
    Posts
    120

    Default

    Yes, I noted that comment in the page:

    Keep in mind that your heat pump can only perform one task at a time so if you are using it for both heating, cooling and/or pool heating, it is better to have a separate hot water heat pump.
    It took me a couple of reads before it clicked: they are saying that the system can't cool and heat at the same time. Which... duh. So you can't use it to make hot water and run cool water through a hydronic system, or cool water for the house and heat the pool... That makes sense. But in your case it sounds like you only care about heating, so it could be an option.

    I'll be interested to hear what you learn, keep me posted
    Owen in Melbourne

  8. #8
    JB1
    JB1 is offline
    1K Club Member
    Join Date
    Jun 2012
    Location
    Melb
    Posts
    1,885

    Default hydronic radiator panels connected to heat pump?

    I’m a big fan of hydronic, I have gas hydronic in Victoria.

    At this stage, I find it cheaper to run my gas hydronic system than my ducted RC air cond, furthermore radiant heating is so much better.

    In future, I will have to consider a heat pump for my hydronic system.

    Heat pumps are fine for my slab heating as the water temp is only 45degs or so.

    The issue with heat pumps is that it struggles to heat water more than 55 or so degrees. I’m assuming efficiency will suffer if the temp is high.

    Currently my radiator panels is fed water at 80degs and it’s already slow enough, though not really an issue as I set timers in the morning and at night.

    I suppose if you’re willing to wait hours to heat up a room with 55deg hydronic panels, then that’s ok. It’s a reality for me in future.

    Personally, if it’s only a couple of rooms, as much as like hydronic, I think split systems are the way to go.

    Having said that, if you were going with heat pump hws anyway and are happy to DIY (and not too fussy with plumbing regulations) you could try one room first. Panels are pretty cheap.

    You’ll need to plumb the ‘cool’ water from the hydronic panels back into the heat pump water supply (without mixing cold water from the mains).


    Slk

  9. #9
    Senior Member ForeverYoung's Avatar
    Join Date
    Jun 2021
    Location
    Perth Hills WA
    Posts
    268

    Default

    Thanks JB1
    I find it cheaper to run my gas hydronic system than my ducted RC air cond, furthermore radiant heating is so much better.
    Yes, I agree, radiant heating is much more pleasant.
    But, bottle gas here, which is more expensive than plumbed 'town' gas.

    Heat pumps are fine for my slab heating as the water temp is only 45degs or so.
    The issue with heat pumps is that it struggles to heat water more than 55 or so degrees. I’m assuming efficiency will suffer if the temp is high.
    It is sounding like heat pumps for HW are a different design than those for hydronic heating?
    It seems a lot of people are now using heat pumps for HW as they are a more efficient use of electricity.
    So I was hoping, in vain it seems, that a new heat pump for a new HWS could also be used for some panel heaters.

    Gas is more of an issue on the East coast where the gas cartel has exploited the market and are charging the locals international prices.
    Here in WA 15% of domestic gas is reserved for domestic consumption, tho I suspect they will continue to put up the price under the guise of 'parity'.

  10. #10
    JB1
    JB1 is offline
    1K Club Member
    Join Date
    Jun 2012
    Location
    Melb
    Posts
    1,885

    Default

    Quote Originally Posted by ForeverYoung View Post
    Gas is more of an issue on the East coast where the gas cartel has exploited the market and are charging the locals international prices.
    Here in WA 15% of domestic gas is reserved for domestic consumption, tho I suspect they will continue to put up the price under the guise of 'parity'.
    I'm hoping that the Vic Government will do a similar thing.

    There may be a revolt if there isn't as 80% of houses in Vic use gas.

    Yes, heat pumps for HW is different to hydronic heating. here's an explanation.

    https://dpphydronics.com.au/is-a-hea...eating-system/

  11. #11
    Senior Member
    Join Date
    Aug 2020
    Location
    Melbourne
    Posts
    120

    Default

    Here's another thing I realized which may help explain the differential you see between heat pump HWS and heat pump hydronic systems: in the hot water system, you are heating water that's contained inside a well-insulated tank. The insulation is there to hold the heat in and keep the water warm for as long as possible before you dispense it from a tap. As a result, you shouldn't need that much heating capacity to do it. You bring the water up to temperature and then shut off, and the insulation should hold it there for awhile.

    Contrast with a hydronic heat system, which is designed to dump heat into the rooms as fast as it can. The water will cool down quickly and constantly need to be reheated. That would take a lot more heating capacity, in a normal house application, where there are usually a few panels. Apparently a typical hydronic system would be a bit over 100L of water total. If you look at that renew.org.au article I linked to, you'll see that even for their small house, they needed two heat pump condensers in order to get enough grunt to warm the house. So while in theory your idea of just hooking up a measly two panels to your HWS might be manageable, I'm guessing that it is such a rare case that the necessary components to implement it aren't really available off the shelf.
    Owen in Melbourne

  12. #12
    Senior Member
    Join Date
    Aug 2020
    Location
    Melbourne
    Posts
    120

    Default

    Quote Originally Posted by JB1 View Post
    Yes, heat pumps for HW is different to hydronic heating. here's an explanation.

    https://dpphydronics.com.au/is-a-hea...eating-system/
    Nailed it - the HWS heat pump is only 1kw capacity, whereas a hydronic system heat pump could be up to 20kw. So they're saying it makes sense to let your hydronic heat pump heat your HW tank, but no chance of going the other direction.
    Owen in Melbourne

  13. #13
    Senior Member ForeverYoung's Avatar
    Join Date
    Jun 2021
    Location
    Perth Hills WA
    Posts
    268

    Default

    Quote Originally Posted by JB1 View Post
    I'm hoping that the Vic Government will do a similar thing.

    There may be a revolt if there isn't as 80% of houses in Vic use gas.
    It's up to the Fed cause all the cause going to export is mainly from Qld.
    There should be a Fed gas reserve (and coal for that matter).

    Yes, heat pumps for HW is different to hydronic heating. here's an explanation.

    https://dpphydronics.com.au/is-a-hea...eating-system/
    Thanks.

    Quote Originally Posted by autojack View Post
    Nailed it - the HWS heat pump is only 1kw capacity, whereas a hydronic system heat pump could be up to 20kw. So they're saying it makes sense to let your hydronic heat pump heat your HW tank, but no chance of going the other direction.
    Yes, that is the way I read it (tho it was badly written).
    Saves me reading that Renew article

    I tried a hydronic expert shop here in Perth; in the end I had to email them.
    Here is their full & technical reply:
    To answer your question, no you won't be able to!!

Similar Threads

  1. Hydronic heating (radiator Panels) piping type
    By zeroasylum in forum Heating & Cooling
    Replies: 1
    Last Post: 26th Nov 2018, 07:20 PM
  2. Hydronic radiator on existing HWS?
    By Smurf in forum Heating & Cooling
    Replies: 1
    Last Post: 23rd Aug 2010, 12:22 PM
  3. Hydronic (radiator) heating tips ?
    By Justin in forum Heating & Cooling
    Replies: 3
    Last Post: 27th Jun 2010, 04:21 PM
  4. Hydronic radiator panel leak
    By ednaruby in forum Plumbing
    Replies: 4
    Last Post: 3rd May 2010, 10:27 AM
  5. Replies: 4
    Last Post: 1st Jun 2008, 06:29 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •