ASHP: lagging pipes in loft

lovesgshp

gterr wrote: »

Yes, I do realise this. But electricity consumption is also correlated with flow temp. So, I need to know how much temp compensation is strictly needed to maintain target temps:
Because of the mixed system, you do need to have the flow/heat store temps increased.

If the curve is too steep then when outside temps fall and flow temp rises the system may be using a higher flow temp than necessary (and maintaining a primary store of water at this higher temp), resulting in unnecessarily high usage of elec.
Also, if the curve is too steep then when outside temps rise, and flow temp decreases, we may end up with a flow temp that is too low to maintain our target temps.
Remember, that as the temp outside decreases, the heat store will increase its temperature, to suit required demand, but as it decreases, then its sensor will also reduce the demand on the pump, as it is higher than what is required.

I've been taking meter readings every 12 hours at 9am and 9pm, and with the original heat curve (V=22, H=55) we were using more units between 9pm and 9am than we were in the daytime between 9am and 9pm. Is this because we are losing a heck of a lot of heat from the building, or is it because the system is maintaining a higher-than-needed temp in the primary store?
As above, it is heating the water, due to lower night temperatures, but cutting back in the day to compensate

Our system is complicated by being a mixture of UF coils and rads, each of which really needs a different flow temp. (And then we've got our own idiosyncratic plumbing - lack of bypass valve etc., and timer/stats in every UF zone - which further complicates the issue and probably compromises the economics.)
In my honest view, the system internally has been designed/planned by someone who is usually only used to conventional heating systems, as it is so complicated.

The thing that stops me making too free with the heat curve is that surely Worcester-Bosch have done no end of research and their recommended heat curves ought to be optimal, and should be better than anything I can do by trial and error and with my lack of preofessional knowledge.
These units have been going for many years, so, virtually all problems have been resolved. Have just checked my GSHP, and it has been running for about 12hrs a day over the last week, as temps are similar to yours.

Geotherm: Many thanks for emailing the simulation software for the Rego 800. I will have a look at this this weekend.

Many thanks for your continued interest and support with all this!

The timers and stats, seem to be the main problem. As Alessandro in our office has said, he thinks the flow is restricted in the radiator circuit and the cold flow is cooling down the heat store.We got down to 35kwh earlier, so virtually all is pointing to the rad circuit.
Perhaps he should come over and sort it out!!
Brain hurts!!!:eek:

gterr

Geotherm wrote: »

The timers and stats, seem to be the main problem. As Alessandro in our office has said, he thinks the flow is restricted in the radiator circuit and the cold flow is cooling down the heat store.We got down to 35kwh earlier, so virtually all is pointing to the rad circuit.
Perhaps he should come over and sort it out!!
Brain hurts!!!:eek:

Hi Geotherm,

Sorry your brain hurts: mine does too!

Let's take a break over Christmas.

But just before we do can I ask one more question?
You know this business of maintaining adequate flow by leaving the rad TRVs open all the time, but using a timer to control when the rads come on? Well, I'm not clear how that works, given that the rad circuit has its own pump. What happens when the pump is off? How is flow still maintained?

As far as I can tell the rad plumbing and UF plumbing are in series. However, there are two pumps, and two motorised valves (one just before the first radiator, the other just before the UF manifold). This suggests to me that someone had the idea that the rad system and the UF system could be used independently - which makes perfect sense. Do you think there might somewhere be some piping I can't see, and that in fact the two systems are not in series, or is it just that the plumber made a mistake and omitted a vital branch (and/or the elusive bypass valve?)

I'll get back in touch in the new year, than maybe we should charter a plane?

All the best!

lovesgshp

gterr wrote: »

Hi Geotherm,

Sorry your brain hurts: mine does too!

Let's take a break over Christmas.
No problem, I work every day!!

But just before we do can I ask one more question?
You know this business of maintaining adequate flow by leaving the rad TRVs open all the time, but using a timer to control when the rads come on? Well, I'm not clear how that works, given that the rad circuit has its own pump. What happens when the pump is off? How is flow still maintained?
Flow is not maintained, when the pump is off, it just reverts to the UFH coils. The heat deltas will still try to keep the heat store at temperature required.

As far as I can tell the rad plumbing and UF plumbing are in series. However, there are two pumps, and two motorised valves (one just before the first radiator, the other just before the UF manifold). This suggests to me that someone had the idea that the rad system and the UF system could be used independently - which makes perfect sense. Do you think there might somewhere be some piping I can't see, and that in fact the two systems are not in series, or is it just that the plumber made a mistake and omitted a vital branch (and/or the elusive bypass valve?)
It does make some sense.but only the original plumber/system designer would be able to explain the setup.As I have said before, at least 70% of the heating circuits need to be opened fully.

I'll get back in touch in the new year, than maybe we should charter a plane?

Thats no problem, you can get in touch anytime.

All the best!

Alessandro, has asked me to keep him updated on how the system is performing.

gterr

Geotherm wrote: »

Alessandro, has asked me to keep him updated on how the system is performing.

Will do!

Have emailed the project manager from the original build to see if we can get the original plumber back to explain the installation, and to ask who pays for this. If we can't get original plumber I'll try to get the replacement plumber who - allegedly - checked and commissioned the pump ready for RHI (if RHI ever happens).

You are definitely right about the flow being impeded. Been struggling all day to get Lounge up to temperature. Timer switched rads on at 5pm, and almost immediately Lounge came up to temp (despite the gallons of cold water entering system).

I think we need to bite the bullet and get the plumbing altered if necessary. I would like to end up with a system where we can have full control over the rad circuit (and for the most part have this turned off) without the UF circuit suffering.

Cheers!

gterr

Happy New Year, all!

OK: Just a quick update:

Spoke to project manager of the new build (not so new now!) and he contacted the main contractor and the second plumber (you may remember that the original plumber was replaced after the pump had been installed but before commissioning) before Christmas asking them to make contact a.s.a.p.

Nothing happened, so I have now issued an ultimatum to all parties that _someone_ has to take the responsibility for sorting the system out. I have given a deadline of 25th January after which I will take legal advice on obtaining redress plus compensation. I have two goals:
1. Have the whole installation inspected, and if necessary have the plumbing altered so that the system works efficiently (instal by-pass valve??)
2. Be given a commissioning certificate plus whatever other paperwork is required to obtain RHI payments if/when they start.

Just had the second plumber on the phone. He says he doesn't see why a by-pass valve would be required, and the problem of cold water flooding the system when the rad circuits open is dealt with by the buffer store. I tried to explain about the pump needing 70% flow but wasn't able to convince him. He did say that the first plumber should not have plumbed the rad circuit and U/F manifold in series, but since both bits have a motorised valve that's OK anyway. (???)

He also says he cannot provide commissioning or other paperwork since he wasn't responsible for the bulk of the installation (though he did put his name as installer and commissioner for the MCS certificate we received.) he suggests I phone the MCS people and see just what they will need to claim RHI payments if these ever start.

I asked second plumber if first plumber (who is still around, apparently) would be able to give us a diagram of the installation, he said almost certainly he never did one. Second plumber suggested _I_ should obtain a diagram of my current installation and what I think is wrong. Politely informed him I am not a plumber!

Can anyone who has followed this thread give me a short paragraph to pass on to plumber to explain what my problem is and why by-pass valve might help?

Also, anybody know what will be required in the way of paperwork to get the RHI payments if these become available. I do have my MCS certificate.

And Geotherm... Looks like you might get that holiday after all!

lovesgshp

Sorry that you are getting such negative replies from your people.
Think you should copy the reply from Alessandro to the plumber!!
I will keep him updated with the conversation for info on the problem as he has asked and let you know.

gterr

Thanks, Geotherm,

I think our second plumber would agree with Alexandro. They both say that a buffer tank should deal with the problem of cold water entering the system when the rad circuit opens. And we _do_ have a buffer tank, so based on that we shouldn't have a problem and don't really have a valid complaint.

However, I am still concerned that we may have a more fundamental problem with the pipework. I would have expected the plumbing to be:

HP>buffer tank> T piece.
Then two branches from T piece, one to the rads and one the the UF manifold, each with a motorised valve and a circulating pump. Then return via buffer tank to HP. (And not sure if either or both should have by-pass valves.)

However, I can't see this T-piece anywhere and as far as I can make out (and I am NOT a plumber) the whole system is in one big loop:
HP>buffer tank>rad circuit>UF manifold>return to buffer tank>return to HP.

This would explain why cold water from the rad circuit flows through the UF circuit. However, this can't be right and I think I must be over-simplifying, otherwise how would water ever make it round the complete circuit if either of the two motorised valves closed, or if either of the circulating pumps stopped?

That's why I really need a plumber to actually LOOK at what we've got, and so far nobody at this end is volunteering!

I posted some photos early on in this thread. I'm not sure if these would allow anyone reading this to comment on the pipe layout.

Cheers

lovesgshp

This is the reply I had from the last update I sent to Alessandro.
Uhm... It's really hard to understand from here!
If this customer was in Italy I would have prepared a quote for an inspection control.
In this case I recommend him to contact the service center officer, who probably recommend a good technician.